AQUAREAD 10401-02024 AP-Pro Multiparameter Water Quality Probe Instruction Manual

AQUAREAD 10401-02024 AP-Pro Multiparameter Water Quality Probe

Product Information

Specifications

• Model: 10401-02024 Rev F
• Date of Revision: December 14th, 2023
• Manufacturer: Aquaread
• Address: Bridge House Northdown Industrial Park, Broadstairs Kent, CT10 3JP ENGLAND
• Contact:
  • Phone: +44 1843 600 030,
  • Website: www.aquaread.com

Product Usage Instructions

1. Introduction

Read through the entire manual before operating the equipment to ensure proper understanding of its functionalities.

2. What’s in the Box?

Check the contents of the package to ensure all components are present.

Refer to specific sections in the manual for details on batch calibration of smart electrodes, cleaning system, and calibration vessel.

3. Aquameter Battery Installation and Care

Follow the instructions provided for installing and maintaining the battery of the Aquameter.

4. Overview of the Operating System

Understand how to switch on the device, set language preferences, and configure the clock.

5. Connecting an AP-PROTM

Learn how to connect an AP-PROTM device and deploy it correctly as per Section 18.

6. Taking Measurements

Follow the guidelines for taking accurate measurements using the equipment.

7. Depth Measurement

Refer to the manual for instructions on depth measurements, including differential depth measurement and depth calibration.

FAQs

• Q: Can this equipment detect harmful bacteria or toxins in water?
  • A: No, the equipment cannot detect harmful bacteria or toxins. It is recommended to always treat suspect water before consumption.

Instruction Manual
for the
Aquaprobe® AP-ProTM Multiparameter Water Quality Probe
and associated Aquameter®, Utilities & Accessories
Document No. 10401-02024
Revision: F
Date: December 14th, 2023
Aquaread® Ltd
Bridge House Northdown Industrial Park
Broadstairs Kent
CT10 3JP ENGLAND Phone: +44 1843 600 030 www.aquaread.com

Aquaprobe® AP-ProTM Instruction Manual

10401-02024 Rev F

PROPRIETARY NOTICE
The information disclosed within this document or separately supplied in furtherance of this document includes proprietary rights of Aquaread® Ltd. Neither this document nor the information disclosed herein or of a supplementary nature shall be reproduced or transferred to other documents or used for any other purposes, except as specifically authorised in writing by Aquaread® Ltd. Copyright 2023 Aquaread® Ltd. All rights reserved.
SOFTWARE LICENCE AGREEMENT
By using the Aquameter®, its associated probes and PC based software (AquaLink), you agree to be bound by the terms and conditions of the following software licence agreement. Please read this agreement carefully.
Aquaread® Ltd grants you a limited license to use the software embedded in the devices (the “firmware”) in binary executable form in the normal operation of the products. Title, ownership rights and intellectual property rights in and to the software remain in Aquaread® Ltd.
You acknowledge that the software is the property of Aquaread® Ltd and is protected under British copyright laws and international copyright treaties. You further acknowledge that the structure, organisation and code of the software are valuable trade secrets of Aquaread® Ltd.
You agree not to decompile, dissemble, modify, reverse assemble, reverse engineer or reduce to human readable form the software or any part thereof or create any derivative works based on the software.
RECYCLING
Any product bearing this symbol must be handed over to an applicable collection point for the recycling of electrical and electronic equipment. By ensuring this product is disposed of properly, you will prevent possible adverse consequences for the environment which could be caused by inappropriate waste handling. Note: For return for recycling, please contact Aquaread® Ltd for instructions on how to return end-of-life equipment, accessories, and all auxiliary items for proper disposal.
WARNING
Favourable indications made by this equipment do not guarantee water is safe for human or animal consumption. This equipment can not detect the presence of harmful bacteria or toxins. If in doubt, ALWAYS TREAT SUSPECT WATER PRIOR TO CONSUMPTION.
Limitations of Liability
Aquaread® Ltd and its affiliates specifically disclaim liability for any and all direct, indirect, special, general, incidental, consequential, punitive or exemplary damages including, but not limited to, loss of profits or revenue or anticipated profits or revenue or expenses incurred arising out of the use or inability to use any Aquaread® product, miscalibration, loss of data or product failure, even if Aquaread® Ltd and/or its affiliates has been advised of the possibility of such damages or they are foreseeable or for claims by any third party. Notwithstanding the foregoing, in no event shall Aquaread® Ltd and/or its affiliates aggregate liability arising under or in connection with Aquaread® products, regardless of the number of events, occurrences, or claims giving rise to liability, be in excess of the price paid by the purchaser for the Aquaread® product.
TRADEMARKS
Aquaread®, AquaPlusTM, Aquameter®, Aquaprobe®, AP-ProTM, AquaTel®, AquaLinkTM and RapidCalTM are all trademarks of Aquaread® Ltd.
Microsoft®, Windows® and Excel® are trademarks of Microsoft Corporation GOOGLETM is a trademark of Google, Inc. StablCal® is a trademark of the HACH company
Aquaread® Ltd has no affiliation with Microsoft Corporation, Google, Inc. or HACH

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Introduction

This manual covers the setup, operation, calibration and maintenance of the Aquaread ® AP-ProTM. In order to communicate with the AP-ProTM you will need either an Aquaread® Aquameter® running software version 6.20+, an Aquaread® AP-PC Kit connected to a PC running AquaCal® software, or an Aquaread® BlueLink® unit and associated BlueLink® Mobile Device App. In addition, you will need an AP-ProTM extension cable
This manual assumes you will be using an Aquaread® Aquameter®. Instructions for alternative methods of communication (AP-PC Kit and BlueLink®) are available for download from: https://www.aquaread.com/downloads/brochures-and- manuals.

2. What’s in the Box? The AP-ProTM is supplied with the following:
· Calibration Cap · Mounting Bracket and Nut · 600mL of RapidCal Solution · pH Storage Cap · 25mL pH Storage Solution · Pot of silicone grease · Lint-free cleaning cloth

2.1. The Aquameter® and the Environment The Aquameter® is designed to be used outdoors and is rated to IP67, that is to say it is waterproof but it is not designed for submersion. In order to prevent accidental dunking or loss, a lanyard is supplied. Please note that the socket on the Aquameter® is only waterproof when the associated plug is fitted. Without the plug fitted, water can enter the socket. Damage caused by water ingress through the socket is not covered by your warranty.
You may notice a small hole on the rear of the unit near the top. This is a waterproof vent for the internal barometric sensor. Do not poke anything in this hole! Doing so will cause major damage to the vent’s waterproof membrane and invalidate your warranty.

2.2. The AP-ProTM and the Environment The AP-ProTM is designed to be fully submerged in fresh or salt water and is rated to IP68, that is to say, it is rated for continual immersion to a depth of 300 meters (1,000 feet).
The AP-ProTM is manufactured predominantly from titanium and carbon fibre, but also contains components made from marine grade stainless-steel, POM, ABS and Nytrile rubber.
Never clean the AP-ProTM with solvents, alcohol or concentrated acid/alkaline based cleaning products such as Decon 90. These products can damage the plastic and rubber components. Damage caused by the use of aggressive cleaning agents or solvents is not covered by your warranty.

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2.3. About the AP-ProTM

The AP-ProTM consists of three main parts: the Probe Body, Sleeve and Measurement Chamber. The Sleeve protects the delicate measurement electrodes whilst the Measurement Chamber provides a stable and repeatable environment in which the electrodes can operate.

The Sleeve, complete with Measurement Chamber can be easily removed from the Probe Body by unscrewing to allow cleaning of the individual electrodes. Likewise, the Measurement Chamber can be removed from the Sleeve to allow cleaning. See image below.

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2.4.

About Smart Electrodes

The AP-ProTM features ‘Smart Electrodes’. These electrodes are made predominantly from titanium and are resin filled for ultimate reliability.

The AP-ProTM comes complete with a DO/EC/Temperature Smart Electrode, a pH/ORP Smart Electrode and a cleaning electrode as standard (centre three above).
In addition, four ‘AUX’ sockets are provided, into which any combination of PRO-ISE (shown above left) or PRO-OPTICAL (shown above right) electrodes can be fitted.
All smart electrodes include a memory chip, which stores information about the electrode, including date of manufacture, last calibration data (GLP) and factory (default) calibration data.
2.4.1. About Batch Calibration of Smart Electrodes All AUX electrodes (with the exception of refined oil and tryptophan) can be ‘batch calibrated’ if required. That is to say, four electrodes of the same type can be fitted to the AP-ProTM and calibrated one after the other in the same session and same solution.
See section Appendix 2. Fitting Electrodes for further information on Smart Electrodes.
2.5. About the Cleaning System The AP-ProTM features a motorised cleaning mechanism, which, when activated, wipes all the measurement electrodes. Any debris that is dislodged from the electrodes during cleaning falls into a gutter at the bottom of the Measurement Chamber and is washed out through the side holes.
This cleaning mechanism is designed for use during calibration and long-term deployment when the Probe is connected to an Aquaread® AquaTel® Telemetry unit or a third party telemetry device.
The cleaning system can be activated from the Aquameter®, BlueLink® unit or AquaCal PC software, which is useful during calibration for removing air bubbles from the electrodes. When connected to an Aquaread® AquaTel® Telemetry unit, the cleaning rate can be programmed remotely from a mobile device.

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2.6. Calibration Vessel

The AP-ProTM is provided with a calibration cap, which is designed to push onto the end of the Measurement Chamber, sealing off the ring of holes and thus forming a low volume (275mL to 325mL, dependent on the number of optional electrodes installed) calibration vessel. It is important to note that for accurate calibration all EC rings must be covered and the calibration vessel should be full to the top.

To create the calibration vessel, apply a very light smear of silicone grease (supplied) to the vertical face of the calibration cap, then press the Sleeve (with Measurement Chamber attached) into the calibration cap as detailed below.

The calibration vessel is now ready for use and should be used for all calibration operations.
When calibration is complete, simply pull the calibration cap off the end of the Measurement Chamber. The Probe will then be ready to use.

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Aquameter Battery Installation and Care

The Aquameter® requires five AA size batteries. To install the batteries, loosen the two screws on the centreline of the rear of the meter and remove the battery compartment lid. Following the battery polarity markings inside the battery compartment, insert five AA cells then replace the compartment lid and tighten the screws.
3.1. Choice of Battery Type Good quality alkaline batteries must be used. Never use rechargeable batteries as they do not provide enough voltage to power the Aquaprobe’s cleaning system.
If the Meter is to be out of use for a long period, remove the batteries to prevent damage due to possible leakage.
3.2. Battery Life A set of fresh alkaline cells will give up to 15 hours use in the AM-200 GPS Aquameter® when used in conjunction with the AP-ProTM. Please be aware however that alkaline battery capacities are extremely temperature dependant. The figures quoted throughout this manual for battery life assume a temperature of 21°C. Battery life can be significantly shorter (by up to 50%) at lower temperatures.
3.3. Battery Condition Icon On all the main Aquameter® screens, a battery condition icon is displayed in the top left corner. The icon shows full when the batteries are fresh, and gradually empties as the batteries are used. When the batteries need replacing, the empty battery icon will flash on and off. If you ignore this, the Meter will automatically switch itself off when the battery voltage becomes too low for reliable operation.
3.4. Battery Saver Functions The Aquameter® is designed to switch off automatically if you do not touch any of the keys for 30 minutes. The only exception to this is if you have activated the Automatic Data Logging feature. In this case, the Meter will continue to operate until either the memory is full or the batteries go flat.
The display on the Aquameter® incorporates a white backlight to improve visibility in lowlight conditions. As on a mobile phone, the backlight switches on each time a key is pressed, and stays on at full brightness for 15 seconds. After 15 seconds, the backlight will fade to half brightness. After a further 15 seconds the backlight will switch off.
During normal operation, if you want to activate the backlight without changing the Meter function, simply press the ESC key.
3.5. Cable Length AP-ProTM extension cables in excess of 50m length include a Cable Booster circuit, which overcomes voltage drop in long cables.
The Aquameter® should not be used with AP-ProTM extension cables longer than 50m as it can not supply sufficient current to drive the booster circuitry.
The Aquaread® AP-PC Kit and the Aquaread® BlueLink® unit both have a higher output capacity and can therefore be used with any length AP-ProTM extension cable.

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Overview of the Operating System

The operating firmware in the Aquameter® has been designed for simple, intuitive use. Similarly, a great deal of development work has been put into simplifying and automating the calibration procedures in the Aquameter® in order to allow normal field operatives (as opposed to trained lab technicians) to achieve quick and accurate results.
If you are used to operating a mobile phone or programming audio/visual equipment using a remote control, you should feel at home with the familiar up/down left/right arrow shaped navigation keys and central OK key.
The tree structure behind the MENU key should also be very familiar. Each item on the menu leads to a sub menu and then either onto further menus or final choices. Each branch of the menu system is navigated using the arrow keys. At each point, selections can be made by either pressing the OK key or the right arrow key.
To reverse along a branch of the menu system, use the ESC (escape) key or left arrow key. After a short time, you should be able to navigate around the entire menu system at speed using just the four arrow keys. If, at any time, you leave the Meter in one of the sub-menu screens, it will automatically back out to the main operating screen after 15 seconds.
4.1. Initial Switch On, Language and Clock Setup To switch the meter on or off, briefly press the red key. Do not hold it down. The meter contains a clock and is capable of operating in several different languages. When switching on for the first time, you must select an operating language and set the clock. The first screen you will see is the Language Selection Screen.

English Italiano Francais Portugues Deutsch Malaysia Espanol Indonesia

To select a language, move the cursor around the list using the arrow keys. To enter your selection, press the OK key or the right arrow key.
The next screen to be displayed is the Time & Date Setting Screen.
Time & Date Time:15:46:37
Date:15/Jun/23

To set the time and date, use the arrow keys to move the cursor around the screen. Use the up and down arrow keys to adjust values. When the time and date are correct, press the OK key. Don’t worry if you make a mistake first time round. You can easily get back to these screens later through the MENU key.

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5. Connecting an AP-ProTM
The AP-ProTM is designed to connect to the Aquameter® AP-PC Kit or the BlueLink® unit using an AP-ProTM Extension Cable. The AP-ProTM Extension Cable features high-pressure metal connectors, which incorporate several O-ring seals at the Probe end. Prior to first connection, the O-ring seals must be lubricated using the silicone grease supplied.

Apply a generous smear of grease to the O-rings where indicated above. Be careful not to get any grease inside the connector near the gold contacts. A small smear of grease should also be applied to the thread on the Probe to allow easy tightening of the collar.
To connect the Extension Cable to the AP-ProTM, align the black dot on the AP- ProTM with the AQUAREAD logo on the stainless steel plug body, then press the plug into the socket and tighten the retaining collar fully. Once the Probe has been connected to the Extension Cable, the Aquameter® can be connected.
Always ensure the Aquameter® is switched off prior to connecting or disconnecting a Probe. Align the AQUAREAD logo on the black aluminium plug body with the red on/off switch on the Aquameter®, then press the plug into the socket and tighten the retaining collar.
Once the AP-ProTM is connected to the Aquameter®, switch the Meter on by pressing the red on/off switch. The Aquameter® should detect the Probe and start displaying readings.
5.1. AP-ProTM Deployment (See also section 18.) When you are ready to deploy the AP-ProTM, remove the mounting nut, fit the mounting bracket then replace and tighten the mounting nut.

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During deployment, the AP-ProTM should not be suspended by the Extension Cable. A non-conductive Mylar or Nylon cord should be attached to the mounting bracket and be used to support the weight of the AP-ProTM.

Deploying the AP-ProTM on a conductive cable (such as stainless steel) is not recommended as this can lead to galvanic corrosion between dissimilar metals.

5.2. Deployment Orientation The AP-ProTM is designed to operate vertically, with the measurement chamber at the bottom and the socket at the top.
This orientation is important to ensure proper operation of the cleaning system, which collects debris in a gutter at the bottom of the measurement chamber, where it is washed away through the holes around the periphery.
If it is absolutely unavoidable, the AP-ProTM may be deployed up to 80 ° off vertical, but installing it at any angle above the horizontal could result in air bubbles collecting in the glass bulb of the pH electrode, which will result in erroneous readings.

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Taking Measurements

The AP-ProTM includes a pH/ORP electrode, which is kept moist by a storage cap. Unscrew the Sleeve and remove the storage cap, which is attached to a red lanyard marked `Remove Before Use / Replace After Use’. Refit the Sleeve and ensure the black Measurement Chamber is fitted.
Switch the Aquameter® on and immerse the AP-ProTM in the sample water, making sure that the water level comes at least half way up the vertical slots in the Probe sleeve.
TIP: Occasional application of a smear of silicone grease or similar lubricant to the Sleeve thread will make fitting and removal easier.
If the AP-ProTM is connected correctly, the meter will read the Probe’s serial number and model number, then will automatically configure itself to display only those readings the current AP-ProTM is capable of taking. Initial Probe readings will be displayed on the meter’s screen along with the current GPS status. The initial data screen for the GPS Aquameter® in conjunction with the AP-ProTM is shown below.

TEMP:018.5°C

ORP:0415.2 mV

pH:06.48

GPS:Acquiring

Left/right arrows at the bottom corners of the screen indicate further data screens are available. To access these screens, simply press either the left or right arrow keys. Any value that is out of range or unavailable will be displayed as dashes. The other four screens available with the standard AM-200 /AP-ProTM combination are shown below.

DO:098.7%

EC:6541µS/cm

TDS:3271mg/L

GPS:3D Pos

SAL:03.57 PSU

SSG:01.3t

GPS:3D Pos

BARO:1013mb

DEPTH:01.75m

Hit [OK] to zero

GPS:3D Pos

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Lat:N51 °21.498 Long:E001°24.323 Alt:00050M 1013mb
Sats in use:09

6.1. What Does It All Mean?
The screens above show the full default range of readings for the AM-200/AP- ProTM combination. If an asterisk (*) character is flashing just below the battery symbol, this indicates that Auto Data Logging is switched on. See Automatic Data Logging in section 8.5.

The table below explains the readings.

Prefix TEMP
pH ORP GPS DO EC TDS SAL SSG BARO DEPTH Lat Long Alt

Meaning Probe Temperature
pH (Acidity/Alkalinity) Oxidation Reduction Potential GPS Status Dissolved Oxygen Electrical Conductivity Total Dissolved Solids Salinity Sea Water Specific Gravity Barometric Pressure Depth above / below zero datum Latitude Longitude Altitude above Sea Level

Units
C or F pH or pHmV mV See section 6.5. %Sat & mg/L µS/cm or mS/cm mg/L or g/l PSU or ppt t mb or mmHg Meters / Feet Degrees & Mins Degrees & Mins Meters or Feet

Items in the Units column marked with an asterisk (*) can be selected as alternative units of measurement in the Settings Menu (see section 9). Items in the Units column marked with a dagger () are auto-ranging, i.e. when the values become too large to display, the units of measurement automatically re- scale.

The EC field can be replaced by its reciprocal value, RES (Resistivity), if selected in the Settings Menu. If selected, readings will be displayed in either cm or Kcm, depending on the value. See section 9 for more details.
6.2. Trend Indication To the right of each reading, (except position, BARO and Depth), a trend indication is given. This consists of either an upwards facing arrow (which indicates the numeric value of the reading is rising), a downwards facing arrow (which indicates the numeric value of the reading is falling) or a two-headed arrow, which indicates a stable reading. Readings are judged to be stable when the variation over a ten second period drops below 1%.
6.3. Global Stability Indication In addition to the individual trend indications, there is a global stability indication, which is displayed when all readings are stable. This takes the form of a flashing double headed arrow which is displayed at the start of the third line of the display.

When taking a set of readings, gently stir the Probe, or raise and lower it in the sample (if

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there is no natural water flow) until the global stability icon appears. The initial display of the global stability icon will be accompanied by a double beep. When this occurs, all values are stable and ready for reading or saving.

6.4. Temperature Compensation
The electrochemical properties of all solutions change with the solution’s temperature. In addition, the response of electrochemical measuring electrodes change with temperature. It is a fundamental, practical requirement in the field of water quality monitoring that test measurements taken at different temperatures can be compared.

In order to facilitate this, the AP-ProTM automatically applies corrections for temperature wherever required.

During three point calibration of the ISE electrodes, the variation in response of the electrodes due to temperature is automatically calculated. During measurement, the variation in response of the electrodes due to temperature is automatically compensated for.

During calibration of the EC electrode, the variation in the calibration buffer solution due to temperature is automatically corrected for. During measurement of EC, the readings can be
displayed without any temperature correction, corrected to 20C, or corrected to 25C (see section 9.1. Setting Units of Measurement)

During calibration of the DO electrode, variations due to temperature and air pressure are automatically compensated for. During the measurement of DO, temperature, air pressure and salinity are automatically compensated for.

During calibration of the ORP electrode, the variation in the calibration buffer solution due to temperature is automatically corrected for. During measurement of ORP however, temperature corrections are not applied as the correction factors are system and chemical dependent and are not easily determined.

ORP potential measurements are mostly made to follow reactions rather than for their own sake. The completion of an ORP reaction is normally accompanied by a sharp change in the ORP millivolts reading. This change is usually much larger than the errors induced by temperature side effects.

During calibration of the optical electrodes, variations in the calibration solutions due to temperature are automatically compensated for. During the measurement, temperature is automatically compensated for.

During calibration of the pH electrode, the small variation in the calibration buffer solutions due to temperature is not compensated for due to the differences in thermal coefficient between various buffer manufacturers. For this reason, the three pH points should be calibrated as close to the buffer manufacturer’s specified temperature as possible (usually 20ºC or 25ºC) although a variation of up to +/-10ºC makes very little difference in reality.

During pH measurement, temperature variation is automatically compensated for.

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6.5. GPS Reception The GPS version of the Aquameter® (AM-200) contains a built-in GPS/GLONAS receiver and antenna. The antenna is situated at the top of the case, just behind the AQUAREAD Logo. For optimum signal reception, the antenna must be able to `see’ a reasonably large amount of the sky. The GPS receiver will not work indoors or when shielded from the sky by any solid structure.
After switch-on, the GPS receiver will automatically start to search for satellites. During this phase, the message GPS: Acquiring will be shown on the bottom line of all the screens. As soon as three satellites are acquired, two dimensional position (no altitude) will be calculated and the message GPS:2D POS will be shown on the bottom line of the screens.
Once a fourth satellite is acquired, altitude will be calculated and GPS:3D POS will be shown on the bottom line of the screens. With a good view of the sky, position should be calculated within ninety seconds of switch-on. To see your geographic position and the number of satellites in use, use the left or right arrow keys to scroll to the Position page.
If you switch the meter on indoors, then carry it outside after several minutes, there may be a considerable delay in acquiring satellites. In this case, switch the meter off, then back on again to reset the acquisition process.

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Depth Measurement

Depth is measured in the AP-ProTM by a pressure sensor mounted inside the body of the Probe. The datum on the Probe for depth measurement is the top edge of the vertical slots cut into the Probe sleeve.

Depth is calculated by subtracting the barometric pressure being measured in the Aquameter® from the water pressure being measured in the AP-ProTM. The pressure differential, once corrected for temperature and salinity (water density), is directly proportional to depth.

The depth measurement system uses the EC sensor to detect when the Probe has been placed in water. All the time the Probe is measuring an EC of zero, the depth will read zero. As soon as an EC value is detected, the meter will start to calculate depth. For this reason, it is important to ensure the Probe is connected to the Meter and switched on prior to submerging the Probe in water.
7.1. Taking Depth Measurements Connect the Probe to the Meter and switch on prior to submerging the Probe in water. Select the Baro/Depth screen as illustrated below. The depth should be reading zero.

BARO:1013mb

DEPTH:00.00m

Hit [OK] to zero

GPS:3D Pos

If the depth is not reading zero (this is possible if the Probe is wet and a low EC reading is registering), press the OK key. You will be asked to confirm by pressing OK again.
Slowly lower the Probe into the water. As soon as the depth value starts to register, you can lower the Probe more quickly.
7.2. Differential Depth Measurement If you want to measure changes in depth, it may be more convenient to zero the depth measurement once the Probe has been submerged.
To do this, press the OK key whilst displaying depth, then confirm. The unit will now read positive or negative changes in depth from the current depth (zero datum).
If the values are positive, the water level has increased from the zero datum. If the values are negative, the water level has decreased.
Using the Automatic Data Logging feature detailed in the following section, it is possible to monitor water levels over a period of time for later recall.

7.3. Depth Calibration
The depth sensor is automatically re-zeroed each time the DO 100% point is calibrated in free air. The depth sensor is factory calibrated and no further calibration is required for the lifetime of the sensor.

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Memory Mode

8.1. Manually Saving Readings When you are happy that the readings are stable (see section 6.3. Global Stability Indication), press the M+ key to snapshot the readings along with the time, date, GLP (calibration) data and position (GPS models only).
As each reading is saved, a numeric memory location `Tag’ will be briefly displayed which you can note down. This Tag can be used to identify readings at a later date, both on the Aquameter® and when using AquaLinkTM software.
8.2. Recalling and Viewing Saved Readings To recall your readings, press the MR key. On entering Memory Recall mode, the most recent Tag and set of readings are displayed first along with the date and time the readings were taken shown on the bottom line of the screen.

M TEMP:012.5°C M ORP:0415.2mV pH:08.21
02/Apr/23 15:04:01

During Memory Recall, an `M’ is flashed in the top left and right corners of the screen alternatively with an up/down arrow and a left/right arrow. This is to indicate that the Meter is in Memory Recall mode and that other screens can be accessed using the arrow keys.
To see earlier readings, press the up arrow key. Just before each set of readings is displayed, the Tag will be briefly displayed. To view all the parameters within one set of readings, use the left/right arrow keys as described earlier. To exit Memory Recall mode, press the ESC key. If no key is pressed for 30 seconds, Memory Recall mode will be automatically cancelled.
8.3. Recalling GLP Data Each time a set of readings is added to memory, the date of the last successful calibration of each electrode is also appended. This is called GLP (Good Laboratory Practice) Data. In addition to the date of the last successful EC calibration, the Calibration Standard value at which the EC was calibrated is also displayed (see section 13.8. Calibrating EC for further details).
To view the last successful calibration date for each electrode for any particular stored reading, enter Memory Recall mode, scroll to the reading you are interested in using the up/down keys, then press the MENU key. The screen below will be displayed.

GLP DATA >pH/REDOX(ORP)
DO/EC Aux Electrodes

Using the up/down keys, select the electrode you are interested in, then press either the OK key or the right arrow key. If, for instance, you selected pH/REDOX(ORP), the screen below would be displayed.

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pH7.00 [31/Jan/23] pH4.01 [07/Feb/23] PH10.0 [07/Feb/23] ORP [09/Feb/23]

This tells you that the last successful calibration, prior to the recorded reading being taken, was January 31st for the pH 7.00 point, February 7th for the pH 4.01 & pH 10.0 point and February 9th for ORP. If the date field is dashed (==/===/==), this means the electrode has never been calibrated.
Pushing the left or right arrow keys will toggle this screen with the calibration report screen.
PH7 Offset:+01.2mV PH4 Slope:56.8mV/pH PH10 Slope:56.3mV/pH ORP Offset:-02.6mV
The calibration report screen displays the calibration report values from the last calibration.
To exit this screen press the ESC key.
8.4. Clearing the Memory The memory within the Aquameter® is capable of storing over 10,000 full sets of readings.
To clear the entire memory, switch the Meter off, hold down the M+ key, then switch the Meter back on. A screen will be displayed asking you to confirm your request. Press OK to clear the memory or ESC to cancel and return to normal operation.
8.5. Automatic Data Logging If you want to save readings on a regular basis, in order, say, to check water quality at a certain location over a period of time, you can set the Meter to record readings automatically.
Readings can be logged for short periods with the Meter permanently displaying readings, or for much longer periods in a Low Power Mode, where the Meter switches itself off between readings in order to extend the battery life.
Please note: Low Power Logging Mode is only available on Meters running version 4.54 firmware and above.
To activate Automatic Logging, press the MENU key. The Main Menu screen will be displayed.
Clean Probe Auto Data Logging Calibration Setup & Install

Select Auto Data Logging by pressing the down arrow key then the right arrow key or the OK key. The Auto Data Logging screen will be displayed.

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Auto Data Logging
Interval:10 Mins Status:OFF

Using the arrow keys to navigate, set the desired logging interval anywhere between 1 and 90 minutes.
To select permanent display logging mode, set the Status to ON. To select Low Power logging mode, set the Status to LOW POWER. To activate the selected logging mode, press the OK key then revert back to the normal operation screen from the Main Menu by pressing the left arrow key.
To indicate that Auto Data Logging is switched on, an asterisk (*) character will flash on and off just below the battery symbol on all the main reading screens. If permanent display logging mode was selected (Status set to ON), the Meter will record a full set of data automatically at the set rate until either the memory is full or the batteries go flat.
If Low Power Logging Mode was selected (Status set to LOW POWER), the Meter will switch itself off 30 seconds after your last key-press. Thereafter it will switch back on at the set rate, stay on for 30 seconds, log the data, then switch back off again. This will be repeated until either the memory is full or the batteries go flat.
If you press any key while the Meter is off between readings in low power mode, the Meter will switch back on. If no further key is pressed, the Meter will switch back off again after 30 seconds and resume Low Power Mode.
You can cancel Auto Data Logging at any time by going back into the screen above and setting the Status to OFF. Auto Data Logging will also be cancelled if you switch the Meter off manually.
8.6. Battery and Memory Duration in Low Power Logging Mode Low Power Logging Mode is specifically designed for long term data logging. In order to estimate battery life and memory usage, the following table can be used.
The battery life figures quoted below are based on fresh, good quality alkaline batteries at a Meter temperature of 21°C or over. Colder Meter temperatures will drastically reduce the battery life. For example, at 5°C, the battery life will be approximately half that quoted.

Logging Rate 90 mins 60 mins 45 mins 30 mins 15 mins 5 mins 1 min

Battery Life (at 21°C) 34 Days 30 Days 28 Days 24 Days 16 Days 7 Days 40 Hours

Memory Duration* 625 Days 416 Days 312 Days 208 Days 104 Days 34 Days 6.9 Days

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So, it can be seen that although the Meter has a maximum data capacity of 625 days, for logging rates above 15 minutes, fresh batteries would need to be fitted every three weeks or so in order to make use of the Meter’s full memory capacity.
Conversely, a logging rate of 2 seconds will fill the Meter’s memory on a single set of batteries (at 21°C or greater).
Useful Tip: If you want GPS data logged in association with your other data, ensure the Meter is positioned face up with a clear view of the sky.

8.7. Important Information About Memory Mode When data is saved in the Meter, it is compressed in raw Probe format. In other words, the same way that it came up from the Probe. When you recall the data in Memory Recall mode, the data is decompressed, then processed for display.
The advantage of this is that the readings will always appear in the current Meter configuration. For example, if you spent a day taking readings with the Meter set to read EC corrected to 25°C, then when you got back you really want to see EC corrected to 20°C or even raw EC, you can do this by simply changing the Meter settings (see section 9.1. Setting Units of Measurement).
The stored data can be displayed any way you want on recall. You are not limited to viewing the data in the same way it was logged. This is a major advantage and allows you to actually store and recall far more parameters than can be displayed at any one time.
The same rules apply when data is output to a PC running AquaLinkTM Software via the USB cable. The data that is output is always as per the Meter’s current configuration. You can output the data as many times as you like in various Meter configurations.

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Setup & Install

To alter the way the Aquameter® displays readings, press the MENU key to get to the Main Menu, then choose Setup & Install. The Settings Menu will be displayed. Please note, the ‘Socket Assignment’ option on this screen is only accessible when a Probe is connected.

Time & Date Units Language Socket Assignment

9.1. Setting Units of Measurement
From this screen choose Units. The Units Menu will be displayed. Remember, you can use just the arrow keys to navigate through the branches of the menus. You don’t need to press OK or ESC at each level.

Units Menu EC/TDS
TEMP/pH/SAL BARO/Alt & Depth

At the Units Menu, you have a choice of which units you want to adjust. Choose the first line if you want to adjust Electrical Conductivity or TDS. Choose line 2 if you want to adjust Temperature, pH or Salinity. Finally, line 3 will give access to Barometric Pressure, Altitude and Depth settings.
Moving the cursor right onto the first line will display the following screen.

Units EC:Ref 25°C
TDS Fact:0.65

The first option on this screen allows you to choose how the Meter displays Electrical Conductivity. There are four options. EC can be displayed as Absolute EC’ without any temperature correction [ABS EC], asSpecific EC’ referenced to 20C [Ref 20C], as `Specific EC’ referenced to 25C [Ref 25C] or as a reciprocal of Absolute EC, which is Absolute Resistivity [ABS RES].
Finally, this screen allows you to set the factor that the Meter uses to calculate Total Dissolved Solids from Specific EC. This is the TDS Fact: (TDS = EC x TDS Fact) and can be set anywhere between 0.00 and 1.00. Default value is 0.65.

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Selecting the second line of the Units Menu will display the following screen.

Units TEMP:°C
pH:pH SAL:PSU

The first option on this screen allows you to change the temperature display between C and F.
The second option allows you to change the pH display between plain pH and pHmV. Plain pH displays normal, temperature compensated pH values in the range 0 – 14.
pHmV displays the actual voltage being generated by the pH electrode in +/- millivolts (mV) over a range of +/- 625mV. This is not temperature compensated.
The last option on this screen allows you to choose between displaying salinity in Practical Salinity Units (PSU), or parts per thousand (ppt), which is the same as grams per litre.
Selecting the third line of the Units Menu will display the following screen.
Units BARO:mb
ALT:Metres

The first line allows you to choose between displaying Barometric pressure in millibars (mb) or in mm of mercury (mmHg).
The second line allows you to choose between displaying altitude and depth in metres (M) or feet (F). Whatever units ALT is set to, DEPTH will follow. Altitude is displayed with respect to mean sea level.
Depth is displayed with respect to the depth zero datum, which can be the water surface or any point at which the depth has been zeroed. See section 7.2. Differential Depth Measurement for further details.
9.2. AUX Sockets The AP-ProTM features four AUX (axillary) sockets into which additional ‘smart’ electrodes may be fitted. Any of the AUX sockets can be fitted with either AP-ProTM Optical electrodes or AP-ProTM ISE (Ion Specific) electrodes. Only one of each electrode type should be fitted during normal operation.
When an electrode has been fitted to an AUX socket (see Appendix 2. Fitting Electrodes for fitting instructions), the electrode’s identification and the latest calibration data stored on the electrode will be transferred to the AP- ProTM.
To view the installed electrode types, select the Socket Assignment option from the Setup & Install screen on the Aquameter®.

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When the Socket Assignment option has been selected, the following screen will be displayed with the names of the installed electrodes shown.

The numbers 1 ­ 6 represent the AUX socket numbers. Only AUX 1 ­ 4 are available on the AP-ProTM.

SOCKET ASSIGNMENTS 1:TURB l 4:CDOM
2:BGA-PC l 5:EMPTY 3:CPHYLL l 6:EMPTY

When connected to an AP-ProTM, this screen can be used for viewing the fitted electrode types only. Any changes to the socket assignments made on this screen will be ignored.

10. Aquaprobe Averaging In all Aquaread multiparameter Aquaprobes, readings are averaged prior to output to an Aquameter, BlackBox or other logging/telemetry device.
All Aquaprobes sample at a two second rate. Parameters that are inherently stable, such as temperature, dissolved oxygen, pH and electrical conductivity are subject to a running average of four readings. That is to say, the most recent four readings are added together and divided by four to give an averaged output value.
ISE electrodes require a little more time to stabilise so are subject to an eight reading running average.
Optical electrodes, such as chlorophyll, blue-green algae and CDOM are subject to a sixteen reading running average. This is not because the electrodes are slow to react (quite the opposite in fact), it is because the distribution of chlorophyll and algae in environmental water is never homogenous.
That is to say, if a sample of water is studied under a microscope, the chlorophyll or algae cells will be found scattered at random throughout the sample. In one area there may be no cells at all, whilst in another area there may be a concentration of cells.
When a reading is taken by an Aquaprobe using an optical electrode, that reading is a very fast snapshot of the cells in front of the electrode. The reading taken two seconds later will be looking at a different set of cells and may result in a higher or lower reading.
For this reason, a longer averaging period is required in order to provide a representative value for the entire body of water.

10.1. Long Term Deployment
In addition to the sixteen reading running average, all Aquaprobes running software version 5.11 and above include a second smoothing algorithm for the optical electrodes, which takes into consideration historical readings in order to provide a smoother, spike free output over a longer period.

During long-term deployment, when connected to a BlackBox or AquaTel telemetry device, each time a reading is requested, the Aquaprobe will wake from sleep, take sixteen readings, then output the averaged values and return to sleep mode.

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The number of samples (Averaging Time Constant) the long-term deployment algorithm takes into consideration is set by default to 128. So, if the reading rate of the controlling device is set to request readings every 15 minutes, and allows the Aquaprobe to enter sleep mode between readings, the readings that are output by the Aquaprobe will take into consideration the values collected over the past two hours (eight sets of 16 readings = 128 readings).

If the Aquaprobe is left powered continuously, the readings that are output by the Aquaprobe will take into consideration the values collected over the past four minutes (128 readings at 2 second intervals = 4.27 minutes).

The Averaging Time Constant can be adjusted between the values of 16 and 192 in increments of 16 using an AP-PC Kit and the AquaRead AquaCal software package (Version 2.07 and above) or by using the Aquaread Mobile App and a BlueLink Bluetooth adaptor.

The image above shows the Averaging Time Constant setup control in AquaCal. After adjusting the time constant value, click the Set button to transfer the setting to the probe.
Please note: In order for the long term averaging to work properly, the Aquaprobe MUST be kept submerged between readings.
10.2. Dip Testing and Profiling In order to allow a fast optical electrode response during dip testing or profiling, the long term averaging algorithm is reset (i.e. all historical data is deleted) each time the Aquaprobe is removed from the water (provided it is switched on).
The Aquaprobe detects that it has been removed from the water by monitoring the electrical conductivity value. If the EC drops to zero, the historical averaging data is deleted and the Aquaprobe reverts to using a normal sixteen value running average, as described earlier in this section.
If the Aquaprobe is subsequently left in the water, it will slowly start to build up historical data again over the number of readings prescribed by the Averaging Time Constant. If a consistently fast response is required, set the Averaging Time Constant to 16.
In all cases during dip testing or profiling, the Aquaprobe should be left to stabilise for a minimum of one minute before recording the readings.

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Calibration

11.1. About Calibration Calibration is a very important part of successful water quality measurement and should be carried out regularly as detailed in each separate section of this manual. A great deal of development work has been put into simplifying and automating the calibration procedures in the AP- ProTM in order to allow normal field operatives (as opposed to trained lab technicians) to achieve quick and accurate results.
As a general rule, pH and EC should be calibrated as close to 25ºC as possible. Optical electrodes should be calibrated as close to their deployment temperature as possible. Please see the individual sections later on, which deal specifically with these electrodes.
11.2. Calibration Vessel The AP-ProTM is provided with a calibration cap, which is designed to push onto the end of the Measurement Chamber, sealing off the ring of holes and thus forming a low volume (275mL to 325mL, dependent on the number of optional electrodes installed) calibration vessel. It is important to note that for accurate calibration all EC rings must be covered and the calibration vessel should be full to the top.
To create the calibration vessel, apply a very light smear of silicone grease (supplied) to the vertical face of the calibration cap, then press the Sleeve (with Measurement Chamber attached) into the calibration cap as detailed below.

The calibration vessel is now ready for use and should be used for all calibration operations.
When calibration is complete, simply pull the calibration cap off the end of the Measurement Chamber. The Probe will then be ready to use.

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The AP-ProTM is designed to be calibrated with the Wiper, Probe Sleeve, Measurement Chamber and Calibration Cap fitted.
The Wiper, Probe Sleeve, end Measurement Chamber form an integral, working part of the Probe’s optical and EC measurement system, and MUST be fitted during calibration and measurement for correct operation.
11.3. Special Notes Concerning ISE Electrodes
The high ionic concentration of pH calibration solutions (buffers), including RapidCal, can cause significant offsets in ISE electrodes.
These offsets are temporary, but best avoided because they can cause significant errors during both calibration and normal operation. For this reason all ISE electrodes are supplied with a red rubber sealing cap.
The caps should be fitted to all ISE Electrodes during pH/ORP calibration, when using RapidCal or using buffers containing interfering ions (i.e. all other ISE calibration solutions other than the one for the specific ISE being calibrated) in order to protect the ISE electrodes from the effects of the buffer solution or interfering ions. At all other times, the ISE electrodes should be left uncovered.
The caps MUST NOT be fitted when calibrating optical electrodes or serious calibration errors will occur due to reflections from the caps.
There must be a functioning pH/ORP-EL fitted for ISE measurement to be valid. Please do not leave the Probe soaking in ISE calibration buffers for extended periods as the pH/ORP electrode will become depleted of ions leading to errors in ISE measurements.

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11.4. Using RapidCal RapidCal calibrates EC at 2570µS/cm and the pH7.00 point simultaneously. Ideally, this procedure should be carried out at the beginning of each day the Probe is to be used. In addition, you should check the DO 100% calibration point and zero any optical electrodes you may have fitted. To use RapidCal:
1. Create the calibration vessel as described in section 11.2. Calibration Vessel.
2. Pour RapidCal solution into the calibration vessel.
3. Remove the storage cap from the pH electrode if fitted Fit the red rubber caps to any ISE electrodes fitted. Wash the Probe in deionised water, then gently lower the Probe into the calibration vessel and screw into place.
4. Activate the Probe cleaning feature in order to remove any air bubbles that may be clinging to the electrodes. To do this, press the MENU key and select CLEAN PROBE.
5. Wait until all readings are completely stable. The longer you can leave the Probe to achieve thermal equilibrium before proceeding, the better. A minimum of two minutes is recommended.
6. Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF ­ 104ºF). The closer to 25ºC the better.
7. Press the MENU key then select Calibration. The following screen will be displayed.

Calibration RapidCal
DO 100% Full Cal

8. Select RapidCal. The screen will change to:
PLEASE WAIT Stabilising
000%

The Meter will wait until all readings are stable, then it will send the RapidCal command to the Probe, where the calibration takes place.

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During calibration, the Calibrating screen is displayed and the progress counter counts up. If the calibration is successful, the counter will reach 100% and the following screen will be displayed.

Calibrating 100%
Press [OK] When calibration is complete, press OK then ESC to return to normal reading mode.
Important If you have ISE electrodes fitted to your AP-ProTM, you must now remove the rubber sealing caps from all the ISE electrodes.
Now the DO 100% saturation point should be checked and if necessary, calibrated in damp air.

11.4.1.

To Check / Calibrate the 100% Saturation Point in Damp Air

1. After calibrating with RapidCaL, remove the Probe from the calibration vessel and wash both the Probe and calibration vessel in fresh water. Shake off any water from the Probe ensuring there are no droplets adhering to the DO membrane.

2. Screw the Probe back into the moist calibration vessel and sit it upright. Do not hold the probe, the heat from your hands will warm the Probe up and interfere with calibration.

3. Wait until the temperature and DO measurements are completely stable. This is very important. If the DO measurement is 100% +/- 1%, there is no need to recalibrate.

4. If recalibration is needed, refer back to the screen shown in item 7 above and select DO 100%.

5. Wait while the Aquameter® carries out the calibration procedure.

6. When the `Calibrating 100%’ screen (shown above) is displayed, press OK then ESC repeatedly to return to normal reading mode.

Finally, if you have any optical electrodes fitted, you should zero them now. To do this:

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1. Pour fresh, clean water into the calibration vessel.
2. Gently lower the Probe onto the calibration vessel and screw into place.
3. Activate the Probe cleaning feature in order to remove any air bubbles that may be clinging to the electrodes. To do this, press the MENU key and select CLEAN PROBE.
4. Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF ­ 104ºF).
5. Press the MENU key then select Calibration. The following screen will be displayed.

Calibration RapidCal
DO 100% Full Cal

6. Select Full Cal. The screen will change to:
Calibration pH/REDOX(ORP)
DO/EC Aux Electrodes

7. Select Aux Electrodes. The screen will change to:

SELECT ELECTRODE 1:BGA-PC l 4:CDOM
2:TURB l 5:EMPTY 3:CPHYLL l 6:EMPTY
The AUX electrodes fitted to each socket will be displayed. Move the arrow to the first socket with an optical electrode fitted then press the OK key to select that electrode. The screen will change to:
CALIBRATE BGA-PC ZERO? [01/Jan/23] Pt-2? [01/Jan/23] GS Factor:01.00

The dates shown to the right of each point are the dates of the last successful calibration.

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8. Select ZERO. The screen will change to:
PLEASE WAIT Stabilising
000%

10401-02024 Rev F

The Meter will wait until the readings are stable, then it will send the calibration command to the Probe, where the calibration takes place. During calibration, the Calibrating screen is displayed and the progress counter counts up. If the calibration is successful, the counter will reach 100% and the following screen will be displayed.
Output:2500mV Calibrating
100% Press [OK] The Calibration Report on the top line displays the voltage output from the electrode in millivolts (mV). This value is stored in the electrode’s memory and can be recalled at any time. See section 11.8. Calibration Data Storage and Retrieval.
Press OK then ESC repeatedly to return to the screen shown in point 7 above.
Select the next optical electrode and repeat the zero point calibration.
Repeat this procedure until all optical electrodes fitted have been zeroed.

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11.5. Calibration Error Messages
If the Aquameter® detects a problem with either the AP-ProTM or the calibration solution during the calibration procedure, an error will be indicated. The chart below shows the possible errors and how to correct them.

Error Message REPLACE DO
CAP BATTERIES TOO LOW NO PROBE RESPONSE READINGS UNSTABLE
OUT OF CAL RANGE
OUT OF TEMP RANGE
CAL ZERO FIRST

Problem
Full re-calibration required or Optical DO Cap needs replacing Battery Voltage is too low for reliable calibration
The Probe is not responding
Readings did not stabilise within the expected period Readings are outside calibration limits (can be caused by low level / incorrect calibration solution). Or the Probe Sleeve is not fitted Temperature is outside 5C ­ 40C limit ISE differential calibration rules not met.
You are trying to calibrate an upper calibration point on an optical electrode without first calibrating the zero point.

Action
See note below.
Replace the batteries
Check connections / cycle power
Top up / replace the RapidCal Top up / check calibration solution is correct type. Ensure the Probe Sleeve is fitted Warm / cool the RapidCal or ISE solution Calibrate the zero point first, then without switching the Aquameter off, calibrate the upper point.

If the ‘REPLACE DO CAP’ error occurs during Optical DO Zero calibration, this usually indicates that the DO Cap needs replacing. Perform a full DO calibration first at DO Zero then at 100% DO. If that does not cure the problem, replace the DO Cap ( see Replacing the Optical DO Cap in section 13.7.).

If the corrective actions shown above for ‘READINGS UNSTABLE’ or ‘OUT OF CAL RANGE’ errors do not work, thoroughly clean the Probe and try again. If the ‘OUT OF CAL RANGE’ error persists, reset the calibration values to Factory Defaults then try again.

If the ‘OUT OF CAL RANGE’ error persists when calibrating EC, check you are using the correct EC Calibration Standard and that the wiper is fitted.

If the ‘OUT OF CAL RANGE’ error persists when calibrating pH, check you are using the correct pH Calibration Standard for the calibration point selected.

If the ‘OUT OF TEMP RANGE’ error persists when carrying out a three point ISE calibration, check your solution temperatures are within the specified limits with respect to each other.

Remember: The Probe Sleeve, Wiper and Measurement Chamber form an integral, working part of the Probe’s optical and EC measurement system, and MUST be fitted during calibration and measurement of these functions for correct operation. If you try to calibrate any of the optical electrodes or the EC without the Wiper, Sleeve or Measurement Chamber fitted, you may get an error message.

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11.6. Resetting to Factory Calibration Defaults

In some cases, if there has been a serious calibration error, the easiest way to rectify the situation is to reset the Electrode to its factory defaults. To do this, first bring up the Calibration screen:
Calibration RapidCal
DO 100% Full Cal

Select Full Cal. This will give you a choice of electrodes:

Calibration pH/REDOX(ORP)
DO/EC Aux Electrodes

Move the cursor arrow to the electrode you want to reset, then press the MR key. If you select Aux Electrodes, you must press OK first to enter the Aux Electrode selection screen. Once in that screen, select the Aux electrode you want to reset then press MR.
A confirmation screen will be displayed.

Are you sure you want to restore the factory calibration values? [ESC]=NO

If you are sure, press the OK key. If you want to change your mind, press the ESC key. If you press OK, you will see a message that says CAL RESTORED.
Once factory calibration defaults have been restored, you should carry out a full calibration of the electrode in question.

11.7. Calibration Reports
At the conclusion of each successful individual electrode calibration, a single line Calibration Report is displayed. This report contains the raw output of the electrode under calibration, uncorrected for temperature.

These values can be recorded and used to track the performance and ageing of the individual electrodes. Please note however, in order to maximise the value of this feature, all calibrations must be performed at the same temperature otherwise the recorded values will not be comparable over time.
11.8. Calibration Data Storage and Retrieval All AP-ProTM Smart Electrodes contain their own memory. All calibration data, including the GLP data, is stored within the individual Smart Electrode’s memory. When an AP-ProTM is connected to a Meter, this data is transferred for display and logging.

This is a major advantage and allows Smart Electrodes to be switched between Probes without the need for full re-calibration.

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In order to recall the calibration data for a certain electrode on the Meter, first select the calibration screen for that electrode. If, for instance, you selected pH/REDOX(ORP), the screen below would be displayed.
pH7.00 [31/Jan/23] pH4.01 [07/Feb/23] PH10.0 [07/Feb/23] ORP [09/Feb/23]

This tells you that the last successful calibration was January 31st for the pH 7.00 point, February 7th for the pH 4.01 & pH 10 points and February 9th for ORP.
Pushing the left or right arrow keys will toggle this screen with the calibration report screen.
PH7 Offset:+01.2mV PH4 Slope:56.8mV/pH PH10 Slope:56.3mV/pH ORP Offset:-02.6mV

The calibration report screen displays the calibration report values from the last calibration. If the calibration report values are zero, this means the electrode has factory default calibration values only and the associated date shown will represent the date of manufacture of the electrode.
To exit this screen press the ESC key.

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pH/ORP Electrode Calibration and Maintenance

12.1. Recognising the pH/ORP Electrode The combined pH/ORP electrode is easy to recognise because it is the only electrode that has slots in the body. The slots allow the gel filled body to be inspected.
12.2. Electrode Removal and Replacement The pH/ORP electrode can be removed from the Probe body by rotating the knurled collar anti-clockwise then pulling the electrode straight out. When replacing an electrode, apply a little silicone grease or similar lubricant to the thread and O rings, then align the black tag on the electrode plug with the black dot next to the socket and push the electrode firmly in. Once the electrode is engaged with the socket, tighten the knurled collar hard down.
Detailed instructions for removal and fitting of electrodes are included in section 25. Appendix 2. Fitting Electrodes
Never immerse an AP-ProTM with the pH/ORP electrode removed. This will cause serious damage to the electrode socket. This is not covered by your warranty.

12.3. Keeping the Electrodes Moist It is very important that the pH/ORP electrode is kept moist when not in use. This is achieved by always fitting the storage cap, which incorporates a sponge that should be soaked in a special storage solution.
The sponge within the storage cap should be moistened with a few drops of pH Electrode Storage Solution (SS-25) each time it is removed and replaced. If a pH/ORP electrode is inadvertently allowed to dry out, it must be re-hydrated by soaking in storage solution for at least one hour prior to use.
12.4. Calibrating pH pH electrodes should be calibrated regularly (exact time between calibrations is dependant upon conditions) to ensure optimum accuracy. Full calibration involves calibrating at pH 7.00 first, then at pH 4.01 and/or pH 10.00. The AP-ProTM allows for both two and three point pH calibration. Should you decide to carry out just a two point calibration, the Probe will automatically calculate and save a calibration value for the un-calibrated third point in order to maintain the electrode’s linearity over the full range of 0 ­ 14.
For best results, calibrate all three points as close to 25C as possible.

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12.4.1.

Special Notes Concerning ISE Electrodes during pH Calibration

The high ionic concentration of pH calibration solutions (buffers), including RapidCal, can cause significant offsets in ISE electrodes. These offsets are temporary, but best avoided because they can cause significant errors during both calibration and normal operation. For this reason all ISE electrodes are supplied with a red rubber sealing cap.

The caps should be fitted to all ISE Electrodes during pH/ORP calibration, when using RapidCal or using buffers containing interfering ions (i.e. all other ISE calibration solutions other than the one for the specific ISE being calibrated and EC calibration solutions) in order to protect the ISE electrodes from the effects of the buffer solution or interfering ions. At all other times, the ISE electrodes should be left uncovered.

The caps MUST NOT be fitted when calibrating optical electrodes or serious calibration errors will occur due to reflections from the caps.

There must be a functioning pH/ORP-EL fitted for ISE measurement to be valid. Please do not leave the Probe soaking in ISE calibration buffers for extended periods as the pH/ORP electrode will become depleted of ions leading to errors in ISE measurements.

12.4.2.

Calibrating the First Point (pH 7.00)

Due to the way in which pH calibration works, the Probe must be calibrated at pH7.00 before calibrating at pH 4.01 or pH 10.00. Never calibrate at pH 4.01 or pH 10.00 before first calibrating at pH7.00.

To calibrate the pH electrode follow these steps:

1. Create the calibration vessel as described in section 11.2. Calibration Vessel.

2. Pour RapidCal or pH7.00 solution into the calibration vessel.

3. Remove the storage cap from the pH electrode. Fit the red rubber caps to any ISE electrodes fitted. Wash the Probe in deionised water, then gently lower the Probe into the calibration vessel and screw into place.

4. Activate the Probe cleaning feature in order to remove any air bubbles that may be clinging to the electrodes. To do this, press the MENU key and select CLEAN PROBE.

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5. Wait until all readings are completely stable. The longer you can leave the Probe to achieve thermal equilibrium before proceeding, the better. A minimum of two minutes is recommended.

6. Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF ­ 104ºF). The closer to 25ºC the better.

7. Press the MENU key then select Calibration. The following screen will be displayed.

Calibration RapidCal
DO 100% Full Cal

8. Select Full Cal. The screen will change to:

Calibration pH/REDOX(ORP)
DO/EC Aux Electrodes

9. Select pH/REDOX(ORP). The screen will change to:
pH 7.00?[01/Jan/23 PH 4.01?[01/Jan/23] PH 10.0?[01/Jan/23] ORP+250?[01/Jan/23] The dates shown to the right of the screen are the dates of the last successful calibration.
10. Select pH7.00. The screen will change to:
PLEASE WAIT Stabilising
000%

The Meter will wait until the readings are stable, then it will send the calibration command to the Probe, where the calibration takes place. During calibration, the Calibrating screen is displayed and the progress counter counts up. If the calibration is successful, the counter will reach 100% and the following screen will be displayed.
Offset: -1.2mV Calibrating
100% Press [OK]

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The top line displays the voltage offset from zero for the pH electrode in +/-millivolts (mV). If this offset goes beyond +/-30mV at 25°C, the pH electrode should be serviced.

This value is stored in the electrode’s memory and can be recalled at any time. See section 11.8. Calibration Data Storage and Retrieval. Press OK then ESC repeatedly to return to normal reading mode.

Remove the Probe from the calibration vessel, empty the calibration vessel, rinse both the Probe and calibration vessel thoroughly with de-ionised water, shake off any excess and dry the Probe and calibration vessel with the special lint-free cloth provided.

12.4.3.

Calibrating the Second Point

The pH electrode can now be calibrated at either pH 4.01 or pH 10.00. If you intend to calibrate at both pH 4.01 and pH 10.00, both points must be calibrated in the same session, i.e. without turning the power off.

If the power is removed after calibrating just one additional point (pH 4.00 for example), the Probe will automatically calculate and save a calibration value for the un-calibrated third point in order to maintain the electrode’s linearity.

To calibrate the second point, pour fresh pH 4.01 or pH 10.00 solution into the calibration vessel then lower the Probe onto the calibration vessel and screw into place. Follow the procedure detailed above, but at step 9, select either pH4.01 or pH10.0, dependent upon the solution you are using. Wait while the Meter stabilises and calibrates. When the `Calibrating 100%’ screen is displayed, the calibration report will display the slope for the
pH electrode in millivolts (mV) per pH unit. If this slope goes below 45mV/pH at 25°C, the pH electrode should be serviced. Press OK then press the ESC key repeatedly to get back to the main display.

Remove the Probe from the calibration vessel, empty the calibration vessel, rinse both the Probe and calibration vessel thoroughly with de-ionised water, shake off any excess and dry the Probe and calibration vessel with the special lint-free cloth provided.

12.4.4.

Calibrating the Third Point

Without switching the Aquameter® off or disconnecting the Probe, pour fresh pH 4.01 or pH

10.00 solution into the calibration vessel then lower the Probe onto the calibration vessel

and screw into place.

Follow the procedure detailed above, but at step 9, select either pH4.01 or pH10.0, dependent upon the solution you are using. Wait while the Meter stabilises and calibrates. When the `Calibrating 100%’ screen is displayed, the calibration report will display the slope for the pH electrode in millivolts (mV) per pH unit. If this slope goes below 45mV/pH at
25°C, the pH electrode should be serviced. Press OK then press the ESC key repeatedly to get back to the main display.

Remove the Probe from the calibration vessel, empty the calibration vessel, rinse both the Probe and calibration vessel thoroughly with de-ionised water, shake off any excess and dry the Probe and calibration vessel with the special lint-free cloth provided.

Dampen the sponge in the storage cap with storage solution and fit it to the pH/ORP electrode. pH calibration is now complete.

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12.5. Errors During Calibration

If a problem occurs during calibration, an error message will be displayed. Refer to Calibration Error Messages in section 11.5. for error message handling.

12.6. Servicing the pH Electrode
1. Remove the pH or combined pH/ORP electrode from the Probe body (see 12.2. Electrode Removal and Replacement).
2. Rinse with methyl alcohol. 3. Replace the electrode. 4. Re-calibrate.

Never place the entire AP-ProTM in methyl alcohol, as this will cause irreparable damage to the DO/EC electrode. Damaged caused in this way is not covered by the warranty.

If the methyl alcohol rinse does not restore the electrode, perform the following actions:

1. Remove the electrode from the body again. 2. Soak in 0.1M HCl for 5 minutes. 3. Rinse in de-ionised water. 4. Soak in 0.1M NaOH for 5 minutes. 5. Rinse in de-ionised water. 6. Soak in pH4.01 buffer for 10 minutes.

If the above procedure still does not restore performance, replace the electrode.

12.7. Calibrating ORP
ORP electrodes should be calibrated at least once a month to ensure optimum accuracy. Full calibration involves calibrating at a single point, either +250mV (at 25C) using a +250mV ORP calibration standard such as Reagecon RS250 Redox Standard, or +229mV (at 25C) using a +229mV ORP calibration standard such as Zobell Solution.

For best results, calibrate as close to 25C as possible. The Probe will automatically compensate for temperature variation in the calibration solution during calibration.

To calibrate the ORP electrode follow these steps:

1. Create the calibration vessel as described in section 11.2. Calibration Vessel.

2. Pour ORP calibration solution into the calibration vessel.

3. Remove the storage cap from the pH/ORP electrode. Fit the red rubber caps to any ISE electrodes fitted. Wash the Probe in deionised water, then gently lower the Probe into the calibration vessel and screw into place.

4. Activate the Probe cleaning feature in order to remove any air bubbles that may be clinging to the electrodes. To do this, press the MENU key and select CLEAN PROBE.

5. Wait until all readings are completely stable. The longer you can leave the Probe to achieve thermal equilibrium before proceeding, the better. A minimum of two minutes is recommended.

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6. Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF ­ 104ºF). The closer to 25ºC the better.

7. Press the MENU key then select Calibration. The following screen will be displayed.
Calibration RapidCal
DO 100% Full Cal
8. Select Full Cal. The screen will change to:
Calibration pH/REDOX(ORP)
DO/EC Aux Electrodes
9. Select pH/REDOX(ORP). The screen will change to:
pH 7.00?[01/Jan/23] PH 4.01?[01/Jan/23] PH 10.0?[01/Jan/23] ORP+250?[01/Jan/23] 10. Move the arrow to the bottom line. If you are using 250mV calibration solution press the OK key to continue. If you are using 229mV calibration solution, move the cursor to the right, then use the up/down arrow keys to select +229. When the correct solution has been selected, press OK. The screen will change to:
PLEASE WAIT Stabilising
000%

The Meter will wait until the readings are stable, then it will send the calibration command to the Probe, where the calibration takes place. During calibration, the Calibrating screen is displayed and the progress counter counts up. If the calibration is successful, the counter will reach 100% and the following screen will be displayed.
Offset: 5.5mV Calibrating
100% Press [OK]

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The Calibration Report on the top line displays the voltage offset between the ORP electrode output and the value of the calibration solution at the calibration temperature in +/-millivolts (mV). During normal operation this offset will be subtracted from the ORP electrode output to give a corrected ORP display.
This value is stored in the electrode’s memory and can be recalled at any time. See section 11.8. Calibration Data Storage and Retrieval. Press OK then ESC repeatedly to return to normal reading mode.
Remove the Probe from the calibration vessel, empty the calibration vessel, rinse both the Probe and calibration vessel thoroughly with de-ionised water, shake off any excess and dry the Probe and calibration vessel with the special lint-free cloth provided.
Dampen the sponge in the storage cap with storage solution and fit it to the pH/ORP electrode. ORP calibration is now complete.

12.8. Converting ORP Readings to the Hydrogen Scale
Electrochemical measurements are ultimately referred to the so-called hydrogen scale, the convention for which is that the electrochemical potential of a hydrogen electrode in contact with hydrogen gas at one atmosphere partial pressure and a solution containing hydrogen ions at unit activity is zero at all temperatures.

The ORP reference electrode used in Aquaread® combination electrodes is a 3MPK1 silver chloride type, and exhibits potentials on the hydrogen scale of:

Temperature 5C 10C 15C 20C 25C 30C 35C 40C

Potential 221 mV 217 mV 214 mV 210 mV 207 mV 203 mV 200 mV 196 mV

Thus, to refer an ORP potential value measured with the AP-ProTM to the hydrogen scale, the appropriate value above should be added to the measured value.

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DO/EC Electrode Calibration and Maintenance

13.1. Recognising the DO/EC Electrode The DO/EC electrode is easy to recognise because it has a plastic central section incorporating four gold EC sensor contacts on the inside facing the rubber wiper. Dissolved Oxygen (DO) is measured at the end of the electrode by the components behind the removable cap. Temperature is measured in the plastic section of the electrode, where the temperature sensor is potted in epoxy resin. Electrical Conductivity (EC) is measured on the inside edge of the electrode by the four gold contacts. The wiper forms part of the EC cell.
13.2. DO Measurement Technique The AP-ProTM features an optical DO sensor. This sensor does not use a liquid electrolyte and has a black rubber gas- permeable membrane.
13.3. Precautions During Use EC measurement is not possible with the Probe central wiper removed as the central wiper forms an integral part of the measurement system.
Never immerse the Probe without the DO Cap fitted. If the components at the end of the DO/EC electrode come into contact with the liquid being tested, serious damage can occur to the DO/EC electrode circuitry.
13.4. Calibrating the DO/EC Electrode Calibration of the EC section of the electrode is normally carried out during RapidCal (see section 11.4. Using RapidCal). EC can be calibrated separately using different EC Calibration Standards, this is covered after the DO calibration section 13.8. Calibrating EC .
The DO section of the electrode should be calibrated at the Zero saturation point at least once every six months. Before each day’s use, the 100% saturation point should be checked in moist air and re-calibrated if necessary. For optimum accuracy, calibrate the DO100% point as near to your sample temperature as possible (within the calibration temperature limits of 5C – 40C).
If you are going to calibrate both the Zero and 100% points at the same time, ALWAYS calibrate the Zero point first, then the 100% point.

13.5. Calibrating the DO Zero Point
1. Create the calibration vessel as described in section 11.2. Calibration Vessel.
2. Pour DO Zero calibration solution into the calibration vessel.
3. Remove the storage cap from the pH/ORP electrode. Fit the red rubber caps to any ISE electrodes fitted. Wash the Probe in deionised water, then gently lower the Probe into the calibration vessel and screw into place.

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4. Activate the Probe cleaning feature in order to remove any air bubbles that may be clinging to the electrodes. To do this, press the MENU key and select CLEAN PROBE.

5. Wait until the temperature and DO readings are completely stable. The longer you can leave the Probe to achieve thermal equilibrium before proceeding, the better. A minimum of ten minutes is recommended.

6. Press the MENU key then select Calibration. The following screen will be displayed.
Calibration RapidCal
DO 100% Full Cal

7. Select Full Cal. The screen will change to:

Calibration pH/REDOX(ORP)
DO/EC Aux Electrodes

6. Select DO/EC. The screen will change to:

Calibration DOZero?[01/Jan/23] DO100%?[01/Jan/23] EC2570?[01/Jan/23]

The dates shown to the right of the screen are the dates of the last successful calibration. 7. Select DOZero. The screen will change to:

PLEASE WAIT Stabilising
000%

The Meter will wait until the readings are stable, then it will send the calibration command to the Probe, where the calibration takes place. During calibration, the Calibrating screen is displayed and the progress counter counts up. If the calibration is successful, the counter will reach 100% and the following screen will be displayed.
Output:4.4 Calibrating
100% Press [OK] The top line will display a value which represents the health of the luminophore. This value should be between 3.5 and 4.5 (at 25°C). If the value returned is less than 3.5, the Optical

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This value is stored in the electrode’s memory and can be recalled at any time. See section 11.8. Calibration Data Storage and Retrieval. Press OK then ESC repeatedly to return to normal reading mode.

If a problem occurs during calibration, an error message will be displayed. Refer to Calibration Error Messages in section 11.5. for error message handling.

13.6. Calibrating the DO 100% Saturation Point in Moist Air 1. After calibrating the DO Zero point, remove the calibration vessel from the Probe and wash both the Probe and calibration vessel in fresh water. Shake off any water from the Probe ensuring there are no droplets adhering to the DO membrane. If droplets remain, blot the membrane with the lint free cloth provided, do not wipe membrane with abrasive material.
2. Screw the Probe back into the moist calibration vessel and sit it upright. Do not hold the probe, the heat from your hands will warm the Probe up and interfere with calibration.
3. Wait until the temperature and DO measurements are both completely stable. This is very important. If the DO measurement is 100% +/- 1%, there is no need to recalibrate.
4. If recalibration is needed, refer back to the screen shown in item 6 above and select DO 100%.
5. Wait while the Aquameter® carries out the calibration procedure.
6. When calibration is complete, the Calibration Report will be displayed.
The top line will display a value which represents the health of the luminophore. This value should be between 0.8 and 1.5 (at 25°C). If the value returned is less than 0.8, the Optical DO Cap should be replaced. This value is stored in the electrode’s memory and can be recalled at any time. See section 11.8. Calibration Data Storage and Retrieval. Press OK then ESC repeatedly to return to normal reading mode.
If a problem occurs during calibration, an error message will be displayed. Refer to Calibration Error Messages in section 11.5. for error message handling.

13.7. Replacing the Optical DO Cap The Optical DO Cap contains a lens, which is coated with an oxygen sensitive luminophore, which is in turn coated with a black rubber compound that provides optical isolation but is permeable to oxygen. Oxygen molecules pass through the rubber into the luminophore. Never touch the black rubber end of the DO electrode as the oils in your skin can block the pores in the rubber coating and stop it from working correctly.
The luminophore within the DO Cap will need replacing every few years, as it is a consumable item. Since the luminophore is an integral part of the DO Cap, the entire DO Cap is replaced. An Optical DO Cap can last up to ten years dependent upon the amount of

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Caution: The inside of the Optical DO Cap is very sensitive to light and can be ruined (bleached) if it is exposed to bright light for any length of time. Never remove the Optical DO Cap from the Probe unless you intend to replace it with a new one. When replacing an Optical DO Cap, do so under subdued light.

To replace the Optical DO Cap, follow these simple steps.

1. Remove the Probe sleeve.

2. Unscrew the Optical DO Cap from the end of the DO/EC electrode by rotating it anticlockwise. Do not touch the exposed optical components.

3. Apply a light smear of silicone grease to the thread and O rings.

4. Remove the new Optical DO Cap from its light-proof bag and quickly screw it onto the end of the DO/EC electrode. Ensure that the cap is screwed fully onto the electrode and that it is done up tight.

5. Carry out both Zero point and 100% point DO calibration as described earlier.

Please Note: It is essential when replacing the Optical DO Cap to calibrate the Zero point BEFORE calibrating the 100% point.

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13.8. Calibrating EC EC calibration is always carried out at a single point. There is a choice of two pre-set calibration standards or you can enter any calibration standard value between 100µS/cm and 99,999µS/cm manually.
The pre-set standards are: Aquaread® RapidCal (EC value 2570µS/cm) and Aquaread® SC35 (35ppt sodium chloride solution), which is specifically for use when measuring EC and salinity in sea water. Both solutions are readily available from all Aquaread® dealers
The calibration solution value you use to calibrate EC should always be chosen to be as near to the readings you expect to see in the field as possible. If you are not sure what values to expect, RapidCal is a good choice as this will give reasonably accurate readings across a wide range of EC values.
SC-35 calibration solution is available from Aquaread® dealers or can be made by adding 35 grams of laboratory grade sodium chloride (99.9% pure) to a 1 Litre volumetric flask and topping it up with DEIONISED water (approx 965g of water) to make 1Litre.

The Probe’s central wiper forms an integral, working part of the Probe’s EC measurement system, and MUST be fitted during calibration and measurement for correct operation. If you try to calibrate the Probe without the wiper fitted, you will get erroneous results. ENSURE LIQUID FILLS THE VESSEL UP TO THE TOP OF THE CALIBRATION CUP so all EC rings are covered and there is at least 1cm of liquid above the top ring.
For best results, calibrate as close to 25ºC as possible. The Probe will compensate for temperature variation in the Calibration Standard during calibration.
1. Create the calibration vessel as described in section 11.2. Calibration Vessel.
2. Pour EC calibration solution into the calibration vessel. It is very important that all four gold EC rings are covered during this calibration and the calibration vessel is full to the top.
3. Remove the storage cap from the pH electrode if fitted. If you have ISE electrodes installed, the red protective caps should be fitted now. Wash the Probe in deionised water, then gently lower the Probe onto the calibration vessel and screw into place.
4. Activate the Probe cleaning feature in order to remove any air bubbles that may be clinging to the electrodes. To do this, press the MENU key and select CLEAN PROBE.
5. Wait until the EC and temperature readings are completely stable. The longer you can leave the Probe to achieve thermal equilibrium before proceeding, the better. A minimum of two minutes is recommended.
6. Ensure the temperature of the solution is between 5ºC and 40ºC (41ºF ­ 104ºF). Ideally, the solution should be as close to 25ºC as possible.

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7. Press the MENU key then select Calibration. The following screen will be displayed.
Calibration RapidCal
DO 100% Full Cal

8. Select Full Cal. The screen will change to:
Calibration pH/REDOX(ORP)
DO/EC Aux Electrodes

9. Select DO/EC. The screen will change to:
Calibration DO Zero?[01/Jan/23] DO 100%?[01/Jan/23] EC R-CAL?[01/Jan/23]

The dates shown to the right of the screen are the dates of the last successful calibration. The value shown on the bottom line next to `EC’ is the value the EC electrode was last calibrated to.

10. Move the pointer down to the bottom line using the down arrow key.

Calibration

DO Zero?[01/Jan/23]

DO 100%?[01/Jan/23]

EC

R-CAL?

[01/Jan/23]

If the Calibration Standard value you are using is already displayed, press the OK key to start calibrating. Remember, if you are using RapidCal solution, the EC value on this line should be R-CAL.
If the value of the EC Calibration Standard you are using is not displayed, press the right arrow key. The bottom line will change to:
Calibration DO Zero?[01/Jan/23] DO 100%?[01/Jan/23] ECR-CAL? [01/Jan/23]

You can now use the up and down arrow keys to select one of two pre-set EC Calibration Standard values (R-CAL or SC-35) or to input any calibration standard value between 100µS/cm and 99,999µS/cm. The value you input should be the calibration solution’s EC value at 25ºC.

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11. Once the correct Calibration Standard value is being displayed, press the OK key. The screen will change to:
PLEASE WAIT Stabilising
000%

12. If the calibration is successful, the counter will reach 100% and the following screen will be displayed.
Cell constant:0.90 Calibrating 100% Press [OK] The Calibration Report on the top line displays the EC Cell Constant. This value is stored in the electrode’s memory and can be recalled at any time. See section 11.8. Calibration Data Storage and Retrieval. Press OK then ESC repeatedly to return to normal reading mode.
Special Notes: If you have selected a Calibration Standard value other than R-CAL, then you subsequently use the RapidCal calibration technique described in section 10, the Calibration Standard value will automatically be reset to R-CAL.
The Calibration Standard value is stored in the electrode, not the Meter. If you use one Meter with several different Probes, you will have to set the Calibration Standard value for each Probe individually during calibration.
If you select a Calibration Standard value but do not press OK, the information will not be sent to the Probe and the change will not be registered.
13.9. Verifying EC Calibration Due to the fact that debris and air bubbles can adversely affect EC calibration, it is advisable to verify calibration has been properly achieved. To do this, follow item ten above with this procedure.
1. Activate the cleaning system. 2. Press the ESC key repeatedly to get back to the Main Menu. 3. Go into settings and make sure EC is set to read with reference to 25ºC. If it’s
not, set it that way. See section 9.1. Setting Units of Measurement. 4. Go back to the main screen, wait until the temperature and EC readings are
stable, then check that the EC is reading +/- 1% of the Calibration Standard value. 5. If the EC reading is outside the 1% limit, recalibrate, this time leaving more time for stabilisation.

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If you can not successfully verify the EC calibration after several attempts, replace the Calibration Standard. If the problem persists, strip the Probe down as described below and thoroughly clean the EC contacts.

13.10. Errors During Calibration
At the beginning of the calibration routine, a sanity check is done. If the Probe detects that the Calibration Standard value set and the Calibration Standard being used differ, the ‘OUT OF CAL RANGE’ error will be reported. If any other problems occur during calibration, an error message will be displayed. Refer to Calibration Error Messages in section 11.5. for error message handling.

13.11. Cleaning the EC Contacts
On a regular basis, thoroughly clean the four gold EC contacts situated on the inside face of the DO/EC electrode with a soft cloth or toothbrush and non- abrasive detergent. Never use solvent or alcohol based products to clean the DO/EC electrode. After cleaning, replace the wiper and Probe Sleeve and re- calibrate.

13.12. Calibrating Temperature
The AP-Pro’s temperature sensor is built into the oval resin pocket located on the back of the DO/EC sensor. The temperature sensor is extremely linear and by default is set up to read within +/- 0.5°C of the true temperature, which is ample for most applications. If, however, your application requires a better absolute temperature accuracy, you can recalibrate the temperature sensor to the nearest 0.1°C by applying a temperature offset.

To calibrate the temperature sensor, remove the Measurement Chamber and Sleeve from the AP-ProTM then set the Probe up in a container of water with a known temperature. This would normally be a temperature controlled bath that is fitted with a calibrated thermometer and a circulation device.

The AP-ProTM can be calibrated at any temperature you choose, and should be calibrated as close as possible to the typical temperatures that will be encountered during normal use.

Once the Probe is set up in the water bath, switch the Aquameter® on wait until the temperature reading has been completely stable for at least five minutes. Make a note of the temperature displayed on the Aquameter® and compare this to the actual temperature of the water bath as displayed by the calibrated thermometer.

Now select the Calibration screen on the Aquameter®.

Calibration RapidCal
DO 100% Full Cal

When this screen is being displayed, press the ‘up arrow’ key eight times in quick succession. This will cause the hidden Temperature Offset screen to be displayed.
TEMP OFFSET:+00.0°C
USE UP/DOWN TO SET HIT [OK] TO SAVE

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Now, using the up and down arrow keys, set the temperature offset that is required to correct the temperature reading.
For example, if the water bath is set to 25.0°C and the Aquameter® is displaying 24.80°C, you should input an offset (or correction) of +00.2°C.
Alternatively, if the water bath is set to 25.0°C and the Aquameter® is displaying 25.30°C, you should input an offset (or correction) of -00.3°C.
When you have input the desired offset, hit the OK key. Now return to the temperature measurement screen. If the offset has been correctly input, the Aquameter® will now be reading the corrected temperature.
The temperature correction offset is stored in the DO/EC electrode and applied at all times going forward.

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Optional Optical Electrodes Calibration and Maintenance

The AP-ProTM is constructed with a titanium Sleeve and plastic Measurement Chamber surrounding the delicate sensing electrodes. The Sleeve and Measurement Chamber can be easily removed by unscrewing to allow cleaning of the individual electrodes, however, The Probe sleeve, Measurement Chamber and wiper form an integral, working part of the Probe’s Optical and EC measurement system, and MUST be fitted during calibration and measurement for correct operation.
All Aquaread® Optical Electrodes are incredibly sensitive. For example, the Turbidity electrode is capable of measuring between 0 and 3000NTU with an internal resolution of greater than 0.1NTU. This means that the electrode is able to detect changes in turbidity that are less than 0.003% of the full range! The other optical electrodes have a similar level of sensitivity.
It follows, therefore, that in order to provide stable, repeatable readings, the environment in which the measurements are made must be completely stable and repeatable.
For this reason, the AP-ProTM includes a removable measurement chamber, which encloses the sensing electrodes and provides a constant, repeatable environment during both calibration and measurement.
In order to obtain consistent results, the measurement chamber must remain physically constant during both calibration and measurement. It is therefore essential that Probe sleeve, wiper and measurement chamber are fitted during calibration and operation of all types of optical electrodes. ENSURE THE CALIBRATION VESSEL IS FULL AND ALL EC RINGS ARE COVERED.
If an optical electrode is calibrated under one set of conditions then used to measure under another set of conditions, the readings will naturally be erroneous, especially at low concentrations.
A perfect example of this is calibrating with the wiper removed then measuring with the wiper fitted (or vice-versa). By changing the physical characteristics of the measurement chamber, you also change the calibration and response of the electrode.
Another particular problem when trying to measure very low concentrations is air in the form of both visible and microscopic bubbles. These act like tiny prisms and can refract and reflect both the excitation light and the return signal being measured.

14.1. Top Tips for successful measurements using optical electrodes

Always keep the measurement chamber and electrode lenses clean.

Always fit the wiper, Sleeve and measurement chamber during both calibration and measurement.

Always allow the readings to settle completely during both calibration and measurement.

Always try to eliminate air bubbles by activate the self-cleaning mechanism.

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Always calibrate and zero the electrode as close to your sample temperature as possible.
Always zero the optical electrodes directly after installation and just prior to use in clean water bottled still mineral water is ideal.

14.2. Optical Electrode Calibration Sequence Optical electrodes feature either two or three point calibration, dependent upon the type. In all cases however, the lower calibration points is ZERO.
When calibrating any optical electrode, the Zero point must be calibrated first.
If you are performing a two or three point calibration, all calibration points must be calibrated within the same calibration session (i.e. without turning the Aquameter® off or disconnecting the AP-ProTM).
If you attempt to calibrate an upper calibration point without first calibrating the ZERO point, a calibration error will occur. An EC reading must be present for an optical electrode to read. Please see section 10.

14.3. Fluorescent Electrode Grab Sample Correction Factor A unique feature of the Aquaread® fluorescent type electrodes is the ability to include a correction factor based upon a grab sample.
If grab sample data is available, a Grab Sample Factor (GS Factor) can be input on the calibration screen of each fluorescent type electrode in order to improve accuracy the of future readings from that electrode.
See the individual fluorescent electrode calibration sections for more details of the unique GS Factor.

© 2023 Aquaread® Ltd.

www.aquaread.com

Page 54 of 112

Aquaprobe® AP-ProTM Instruction Manual

10401-02024 Rev F

References

• MilliporeSigma | Life Science Products & Service Solutions
• MilliporeSigma | Life Science Products & Service Solutions

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