APERA GroStar GS4 Premium pH/EC Pen Tester User Manual
- June 3, 2024
- APERA
Table of Contents
GroStar™
GS4 Premium pH/EC Pen Tester
User Manual
APERA INSTRUMENTS (Europe) GmbH
www.aperainst.de
Thank you for choosing the Apera GroStar™ GS4 Premium pH EC Pen Tester. This premium pen has been designed specifically for the horticultural market. Since 1991, Apera instruments has been dedicated to providing hi-tech, accurate, lab-grade instruments and sensors. GroStar’s intelligent design reduces the guesswork so you can easily manage your crops success.
Main Features
- Premium combo pH/EC probe measures pH, EC, ppm (500/700) all-in-one unit with minimal maintenance.
- Easy to use design and quick two-point calibration adjustment.
- 3-Color backlit LCD screen gives you clear readings in different modes even in dark environment.
- Durable structure, IP67 waterproof rating, powered by AAA batteries.
- The probe is replaceable, so you don’t have to discard the entire pen when the probe reaches its end of life.
Preparation Before First Use
2.1 Pull out the battery insulation slip, and take off the probe cap.
2.2 Rinse off the probe in clean water, then shake off excess water.
2.3 Calibrate pH and EC. For calibration tutorial, refer to Section 3 and
Section 4.
2.4 If you find the probe cap is dried out, soak the probe in 3M KCL soaking
solution for 5 minutes before use.
2.5 If the tester hasn’t been used for a long time (over 1 month), please soak
the probe in the 3M KCL soaking solution for at least 1 hour, then calibrate
it before measurement begins
pH Calibration
3.1 Power on the pen and remove the probe cap. Always calibrate 7.00 pH first.
3.2 Rinse the probe with clean water and shake off excess water, then submerge
it in the 7.00 pH standard buffer; shake the probe up and down in the solution
for a few seconds and let it stand.
3.3 Hold ****until screen turns green. The pen starts automatic calibration. Wait for “Good” to show up (in 10-15 seconds), indicating the calibration is completed, then the pen returns to measurement mode.
Short press any key while calibrating (in green screen) to cancel calibration and return to measurement.
3.4 icon will show up on the lower left corner of the screen indicating the pen is successfully calibrated. Repeat Step 3.2 to 3.3 to calibrate pH 4 using 4.00 pH buffer, then will show up next to . You can continue to calibrate pH 10 by repeating Step 3.2 to 3.3 using 10.01 pH buffer (sold separately), then will show up to the right of ****.
Calibrating pH 10 is usually not necessary unless your estimated target pH is greater than 8.0 pH.
3.5 / / ****will disappear in 30 days after calibration, reminding you
to recalibrate the tester. We recommend calibratingpH at least once a month to
ensure accuracy. If you feel like the accuracy might be off, simply test the
standard buffers (make surthe buffers are fresh and clean). If a discrepancy
is found, then ittime to calibrate again. 3.6 If the calibration fails, the
screen will turn red. For details, see Section 13 Troubleshooting
Guide.
Always perform at least a 2-point pH calibration to ensure accuracy. Start with 7.00 pH, followed by 4.00 pH immediately. If you happened to turn off the pen before calibrating 4.00 pH, you need to start with 7.00 pH again after rebooting the pen, then 4.00 pH.
pH Measurement
4.1 Power on and remove the probe cap.
4.2 Rinse the probe with clean water and shake off excess water.
4.3 Fully submerge the probe into the solution at least 1 inch deep, make a
quick stir to remove potential air bubbles around the probe.
4.4 Hold the pen and wait for the reading to stabilize ( ****stays on screen),
then record the reading.
4.5 Thoroughly rinse off the probe with clean water, then close the probe cap.
EC Calibration
5.1 Power on and remove the probe cap. Press ****to switch to EC measurement
mode. Rinse the probe with clean water and shake-dry, then submerge it in the
2.77 EC standard solution; shake the probe in the solution up and down for a
few seconds to remove potential air bubbles, then let it stand.
5.2 Hold until screen turns green. The pen starts automatic calibration. Wait
for “Good” to show up (in 10-15 seconds), indicating the calibration is
completed, then the pen returns to measurement mode.
Short press any key while calibrating (in green screen) to cancel calibration and return to measurement.
5.3 icon will show up on the lower left corner indicating the tester is successfully calibrated. will disappear in 30 days after calibration, reminding you to re-calibrate EC. We recommend calibrating the EC once every month to ensure the accuracy. If you feel like the accuracy might be off, simply test the standard solution (make sure the standard is fresh and clean). If the reading is greater than 2.8 EC or smaller than 2.7 EC, then it’s time to calibrate again.
5.4 If the calibration fails, the screen will turn red. For details, see Section 13 Troubleshooting Guide.
6 EC/500ppm/700ppm Measurement
6.1 Power on and remove the probe cap.
6.2 Rinse the probe with clean water and shake off excess water.
6.3 Submerge the probe into the solution, make a quick stir to remove
potential air bubbles around the sensor. Hold still and wait for the reading
to stabilize ( stays on the screen), then record the reading.
6.4 Short press to switch from EC → 500ppm → 700ppm
6.5 Thoroughly rinse off the probe with clean water.
What is EC and its relation to 500ppm & 700ppm?
EC (electrical conductivity) is a measure of the nutrients in the solution.
Low conductivity implies a low nutrient concentration, which usually results
in nutritional deficiencies and slow growth rates of your plants.
A higher conductivity is more food for your plants. However, be careful of
very high levels as delicate plants, cuttings, and seedlings can experience
fertilizer burn if the conductivity is excessively high.
EC, 500ppm, and 700ppm are simply different units preferred by different
markets. 500ppm and 700ppm both originate from EC. Therefore, using EC to
compare and analyze test result is the safest way and will minimize
confusion. Here is how they convert to each other:
1.0 (EC) = 500ppm (500ppm) = 700ppm (700ppm)
2.6 (EC) = 1300ppm (500ppm) = 1820ppm (700ppm)
3.5 (EC) = 1750ppm (500ppm) = 2450ppm (700ppm)
Other Functions
7.1 If necessary, you can manually hold (lock) the reading by short pressing
. Press it again to cancel the hold.
7.2 Long press to switch temp. unit between °F and °C.
7.3 The tester will automatically power off if there is no operation within 10
minutes. If you want to turn off/on the Auto. Power Off function, power off
the tester, and then hold ****for 5 seconds until you see Auto Off or Auto
On. Then it will power on and go to measurement mode automatically.
Probe Cleaning
8.1 The tester is only as accurate as the probe is clean. Always thoroughly rinse off the probe before and after each measurement with clean water in a container or with a wash bottle. 
8.2 For tough contaminants, remove the sensor shield, soak the probe in Apera’s cleaning solution or detergent water for 30 minutes. Then use a soft brush to remove the contaminants. Afterwards, soak the probe in 3M KCL soaking solution for 1 hour. Rinse it off, then re-calibrate the tester before using again.
Probe Storage
9.1 Under regular usage (daily or weekly use), make sure there are several drops 3M KCL soaking solution in the probe cap, and tightly close the cap with the O-ring.
9.2 For long-term storage (you are not going to use the product for more than a month), add 3M KCL soaking solution to the Fill line in the cap and store the probe in it. Close the probe cap tightly with the O-ring.
If you find white crystals inside or outside the probe cap, it is perfectly normal. It is the 3M KCL soaking solution that crystalizes over time by its nature. Just rinse them off and add in new soaking solution. This chemical is not poisonous nor dangerous, and the probe’s performance will not be affected at all.
Battery Replacement
- Pull up the battery cap (might take some force).
- Slide the battery cover along the OPEN arrow to open the cover.
- Open the battery cover.
- Insert the batteries (ALL POSITIVE SIDES FACING UP).
- Press down the battery cover and hold it.
- Slide the battery cover along the LOCK arrow to lock the cover.
- Close the battery cap. Make sure to push it all the way down. The tester’s waterproof rating may be compromised if the battery cap is not tightly closed.
11 Probe Replacement
• Screw off the probe ring, unplug the old probe; plug in the new probe (make
sure to align the connector’s position properly), and screw on the probe ring.
Probes don’t last forever. Every probe will eventually age and fail even if
you don’t use it that often. The typical service life of GroStar probes is
18-24 months depending on the frequency of usage and how well you keep it
clean and properly stored.
We recommend replacing your probe at least every 18 months to ensure the best
accuracy.
The nice thing about GroStar pens is that you can just buy a replacement probe
instead of a whole new tester.
12 Notes
12.1 Never store the probe in pure water such as tap water, RO water,
distilled water, deionized water, etc.
12.2 Never use your finger to touch the glass membrane or use other material
to wipe it.
12.3 Avoid testing in high (>113°F/ 45°C) or low temperature (<41°F/ 5°C)
solutions as it will cause greater measurement error and damage to the probe.
Test your samples and perform calibration close to room temperature as much
as possible.
12.4 Never test oily liquids.
12.5 Make sure the battery cap is completely closed with the O-ring.
Otherwise, the waterproof rating could be compromised.
Tro ubleshooting Guide
| Trouble | Reason | How to fix |
|---|---|---|
| Incorrect calibration order | Power on the tester, calibrate pH 7 first, |
then pH 4.
After pH 4 is calibrated, if you want to calibrate pH 7 again, you need to
reboot the tester.
Poor quality standard solutions| Replace with fresh and clean standard
calibration solutions made by legitimate scientific instrument manufacturers.
Contaminated probe| Clean the probe with Apera’s cleaning solution or
detergent water.
Aged probe| Replace the probe.
Dried out probe| Soak the probe in the 3M KCL soaking solution for at least 1
hour.
Probe is not fully submerged in the solution| Make sure the probe is fully
immersed in the solution at least 1 inch deep.
Air bubbles around the sensor| Make a quick stir in the solution to remove air
bubbles.
Reading is always slowly changing, won’t stabilize.| Contaminated probe| Clean
the probe with Apera’s cleaning solution or detergent water.
Clogged junction| Clean the probe with Apera’s cleaning solution, then soak it
in 3M KCL soaking solution overnight.
Aged probe| Replace the probe.
Testing pH of low iconic strength solutions like tap water, drinking water,
RO water| Be patient, wait for 2-5 minutes to reach a fully stabilized
reading. If still not stabilizing, add 1m1 of 3M KCL solution to 1000m1 of
test solution.
Display similar readings in any solutions or always display 7.0| Broken probe|
If you don’t find any visible damage of the probe and it’s within the 1-year
probe warranty, contact your point of purchase for warranty fulfillment; If
there is visible damage or the probe is more than 1-year old, replace the
probe.
Reading keeps jumping| Probe is not fully submerged in the solution| Make sure
the probe is fully immersed in the solution at least 1 inch deep.
Air bubbles around the sensor| Make a quick stir in the solution to remove air
bubbles.
Probe is not properly connected, or the pin connector is broken.| Check the
probe’s connector, make sure it’s not broken and is correctly connected. Align
the probe and instrument correctly before plugging in. Never force it. Ensure
that the probe connector is not exposed in the air too long.
Calibration is successful, but reading is not accurate| Aged probe| Replace
the probe.
---|---|---
Air bubbles around the sensor| Make a quick stir in the solution to remove air
bubbles.
Clogged junction| Clean the probe with cleaning solution, then soak it in 3M
KCL soaking solution overnight
Comparison with other testers, test strips, or drop tests| To compare with
other testers, make sure to perform a 2-point calibration for all testers in
the same standards, then test a 3rd point. Whichever gives more accurate
reading in the 3rd point standard is the most accurate one. Test strips or
drop tests’ accuracy is not comparable to pH meters’.
Out of range reminder for:
Technical Specs
Range| 0.0 to 14.0 pH,
0 to 10.0 EC,
0 to 7000ppm (700ppm),
0 to 5000ppm (500ppm),
0 to 50˚C (32 to 122˚F)
---|---
Resolution| 0.1 pH, 0.1EC, 10ppm (700ppm), 10ppm(500ppm), 0.1˚F/0.1˚C
Accuracy| ±0.1 pH,
±0.1 EC
±30ppm (500ppm)
±40ppm (700ppm)
±1˚C/±1˚F
Temperature compensation| Automatic
Calibration| pH: automatic 1 to 3 points (7/4/10) *10.01 pH solution sold
separately; EC: automatic 1 point (2.77 EC)
Unit| pH, EC, 500ppm, 700ppm, ˚F, ˚C
Power Supply| 4-AAA alkaline batteries, up to 1000 hours of operation
Backlight| White (measurement); Green (calibration); Red (errors)
Reading hold| Manual
Warranty| Two years for the instrument, one year for the probe
pH probe| Low-resistance lithium glass membrane, double-junction, blue gel
electrolyte
EC probe| Titanium alloy
Successful calibration indicators| M (7.00 pH/2.77 EC), L (4.00 pH), H (10.01
pH)
Low battery reminder|
Waterproof rating| IP67
Reading stabilization icon|
What’s in the box
Accessories
- pH buffer Kit (pH4/7, 250ml, each), item AI1113
- pH buffer Kit (pH4/7/10, 250ml, each), item AI1115
- 2.77 EC Standard Calibration Solution
- 3M KCl storage solution 250ml, item Al1107
- GS1-E pH Probe, item Al58010
- GS2-E Soil pH Probe, item Al58020
- GS3-E EC Probe, item Al58030
- GS4-E pH/EC-Combo-Probe, item Al58040
Warranty
How Long Does the Coverage Last?
Apera Instruments® (Apera) warrants the GroStar™ GS4 Premium pH/EC Combo Pen
Tester (Product) for a period of 24 months for the instrument and 12 months
for the probe from date of purchase by original purchaser or consumer. Proof
of purchase is required for the warranty to be effective (store sales receipt
for Product showing model number, payment, and date of purchase). This
warranty is non-transferable and terminates if the original purchaser/consumer
sells or transfers the Product a third party.
What is Covered?
Apera warrants the Product against defects in material and workmanship when
used in a normal manner, in accordance with Apera instruction manuals. If
Apera is provided with valid proof of purchase (as defined above) and
determines the Product is defective, Apera may, in its sole discretion either
(a) repair the Product with new or refurbished parts, or (b) replace the
Product with a new or refurbished Product.
What is NOT Covered?
This warranty does not apply to equipment, component or part that was not
manufactured or sold by Apera and shall be void if any such item is installed
on a Product. Further, this warranty does not apply to replacement of items
subject to normal use, wear and tear and expressly excludes:
-
Cosmetic damage such as stains, scratches, and dents
-
Damage due to accident, improper use, negligence, careless operation or handling of
Product not in accordance with Apera instruction manuals, or failure to maintain or care for Product as recommended by Apera -
Damage caused by use of parts not assembled/installed as per Apera instructions
-
Damage caused by use of parts or accessories not produced or recommended by Apera
-
Damage due to transportation or shipment of Product
-
Product repaired or altered by parties other than Apera or its authorized agents
-
Product with defaced, missing, or illegible serial numbers
-
Products not purchased from Apera or an Apera-authorized distributor or reseller.
How Do You Get Service?
To begin a warranty claim you must return the Product to the point of purchase
with valid proof of purchase.
Limitation of Liability & Acknowledgments
TO THE MAXIMUM EXTENT PERMITTED BY LAW, THIS WARRANTY AND THE REMEDIES SET OUT
ABOVE ARE EXCLUSIVE AND IN LIEU OF ALL OTHER WARRANTIES, GUARANTEES AND
REMEDIES (ORAL OR WRITTEN, EXPRESS OR IMPLIED). EXCEPT AS PROVIDED IN THIS
WARRANTY AND TO THE MAXIMUM EXTENT PERMITTED BY LAW, APERA INSTRUMENTS IS NOT
RESPONSIBLE FOR SPECIAL, INCIDENTIAL OR CONSEQUENTIAL LOSS OR DAMAGES, OR ANY
OTHER LOSS OR DAMAGES RESULTING FROM SALE OR USE OF THE PRODUCT, OR BREACH OF
WARRANTY, HOWEVER CAUSED, INCLUDING DAMAGES FOR LOST PROFITS, PERSONAL INJURY
OR PROPERTY DAMAGE.
IT IS UNDERSTOOD AND AGREED BY CONSUMER UPON PURCHASE OF A PRODUCT THAT, EXCEPT AS STATED IN THIS WARRANTY, APERA INSTRUMENTS IS NOT MAKING AND HAS NOT MADE ANY EXPRESS OR IMPLIED WARRANTY OR OTHER REPRESENTATION REGARDING THE PRODUCT AND DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE TO THE EXTENT PERMITTED BY LAW. ANY WARRANTIES WHICH ARE IMPOSED BY LAW AND CANNOT BE DISCLAIMED ARE HEREBY LIMITED IN DURATION TO THE PERIOD AND REMEDIES PROVIDED IN THIS WARRANTY.
SOME JURISDICTIONS (STATES OR COUNTRIES) DO NOT ALLOW EXCLUSION OR LIMITATION FOR INCIDENTIAL OR CONSEQUENTIAL DAMAGES, OR LIMITATION ON HOW LONG AN IMPLIED WARRANTY LASTS, SO THE ABOVE LIMITATION OR EXCLUSION MAY NOT BE APPLICABLE. IF ANY PROVISION OF THIS WARRANTY IS JUDGED TO BE ILLEGAL, INVALID OR UNENFORCEABLE, THE REMAINING PROVISIONS OF THE WARRANTY SHALL REMAIN IN FULL FORCE AND EFFECT.
Governing Law; Authority
This warranty is governed by the laws of the state of country where Product is
purchased, without regard to its choice of law principles. Except as allowed
by law, Apera does not limit or exclude other rights a consumer may have with
regard to the Product. No Apera distributor, employee or agent is authorized
to modify, extend, or otherwise change the terms of this warranty.
APERA INSTRUMENTS (Europe) GmbH
Wilhelm-Muthmann-Straße 18
42329 Wuppertal, Germany
Contact: info@aperainst.de
Website: www.aperainst.de
Tel. +49 202 51988998
Documents / Resources
|
APERA GroStar GS4 Premium pH/EC Pen
Tester
[pdf] User Manual
GroStar GS4 Premium pH EC Pen Tester, GroStar GS4, GroStar, GS4, GS4 Premium
pH EC Pen Tester, Premium pH EC Pen Tester, EC Pen Tester, Pen Tester, EC
Tester, GS4 Tester
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References
Read User Manual Online (PDF format)
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