ONSET MX2501 pH and Temperature Data Logger User Guide
- June 8, 2024
- Onset
Table of Contents
ONSET MX2501 pH and Temperature Data Logger
IMPORTANT: The logger is shipped with the pH electrode installed and
submerged in storage solution. The pH sensor must be kept in storage solution
when not being calibrated or deployed in water. The hydration layer
surrounding the sensor starts to break down after 10 minutes if the pH sensor
is not submerged in storage solution or calibration solution, or deployed in
water.
IMPORTANT: The pH electrode is uncalibrated. You must calibrate the
logger as described in step 2 before configuring and deploying it.
Download and open HOBOconnect
- Download HOBOconnect® to a phone or tablet from the App Store® or Google PlayTM. Download HOBOconnect to a Windows® computer from www.onsetcomp.com/products/software/hoboconnect.
- Open HOBOconnect. If prompted, enable Bluetooth® in your device settings.
- Wake up the logger by pushing the switch on the mounting end of the logger into the gap beneath the mounting lanyard (see diagram on back). Tap Devices and make sure the logger appears. If it does not, make sure it is within range of your phone, tablet, or computer.
Calibrate the logger
Before you begin: To complete these steps, you will need deionized or
distilled water, a squirt bottle, calibration solution (also known as buffer
solution), and beakers.
Note: pH values of calibration buffers and samples vary depending on their
temperature. As a result of this, it is important that the logger is
calibrated in buffers that have the same temperature as that of the sample.
Refer to the chart on the calibration buffer bottles or in the logger manual
for the effect of temperature on the buffer pH values.
- Pour each calibration solution into its own beaker (pH 7.00 solution and either one or both of pH 4.01 and pH 10.00 solutions). You need enough solution in the beaker to cover the sensor end cap and closure cap on the logger.
- Unscrew the clear storage cap filled with storage solution and remove it from the logger. Keep the cap filled with storage solution nearby in case you need to reinstall it after calibrating and before deploying the logger.
- Screw the closure cap onto the logger.
- Use a squirt bottle to rinse the pH sensor with deionized or distilled water.
- Tap Devices (if necessary) and tap the logger tile in the app to connect to the logger.
- Tap Calibrate.
- Place the sensor end of the logger in the pH 7.00 solution. Make sure the sensor end cap, temperature sensor, and closure cap are submerged in the solution as shown in the illustration. Tap Start. Follow the instructions on the screen. Once the pH reading is stable, tap Confirm.
- Rinse the pH sensor with deionized or distilled water.
- If you are using the pH 4 buffer, place the sensor end in the pH 4 solution and tap Start. If you are not using the pH 4 buffer, tap Skip and go to step k.
- Once the pH reading is stable, tap Confirm. Rinse the pH sensor with deionized or distilled water.
- If you are using the 10 buffer, place the sensor end in the pH 10 tap Once the pH reading is stable, tap Confirm. If you are not using the pH 10 buffer, tap Skip
- Verify that the slope and offset is acceptable and tap Save. If the slope and offset are not acceptable, then tap the back arrow and repeat the calibration steps in this section as needed
- Rinse the pH sensor with deionized or distilled water.
If you are not deploying the logger immediately, place the pH electrode back into the storage solution. Unscrew the sensor end cap you installed in step c. Make sure the storage solution reaches the marked fill line on the clear storage cap; pour more into the cap if necessary. Carefully screw the clear cap with storage solution onto the logger. Only use storage solution in the clear cap; do not use water. Do not use the copper guard when the pH electrode is in storage solution.
Configure the logger
- Tap Devices and then tap the logger tile in the app to connect to the logger (push the switch on the logger to wake it up if necessary).
- Tap Configure & Start
- Choose the logger settings. Note that the default Bluetooth setting for the logger is Bluetooth Always On, which means it advertises or regularly sends out a Bluetooth signal for the app to receive. This setting uses battery power. You can change this to Bluetooth Always Off, which saves power. When the logger is set to Bluetooth Always Off, it advertises only when you wake it up by pushing the switch on the mounting end of the logger.
- Tap Start to save the settings to the logger. The logger begins logging data based on the settings you selected. If you configured the logger to start or stop logging with the On Button Push option, push the switch on the mounting end of the logger for 3 seconds.
Deploy the logger
Deploy the logger to the location where you will be monitoring the conditions. Remove the clear storage cap from the logger if installed and replace it with the closure cap. If your water sample is Copper guard installed to protect against biofouling prone to biofouling, insert the optional copper anti- biofouling guard around the pH sensor as shown at right. Gently twist the copper guard so that the holes line up with the holes in the sensor end cap and pH electrode. Do not use the copper guard when the pH sensor is being calibrated or in storage solution, or if the sensor is placed in a very small container with still water or in water where copper can affect the environment.
Download data from the logger
- Open HOBOconnect.
- Remove the logger from the water. If the logger is configured with Bluetooth Always Off, push the switch on the logger for 1 second to wake it up.
- Tap Devices, connect to the logger, and then tap Download Data.
- After the download is complete, you can choose to export and share the file. You can also view your files by tapping Data at the bottom of the screen.
For information on using this logger, refer to the complete product manual. Scan the code at left or go to www.onsetcomp.com/support/manuals/22511-mx2501-manual.
References
- HOBOconnect | Onset's HOBO and InTemp Data Loggers
- Technical Support | Onset's HOBO and InTemp Data Loggers
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