Hobo MX2501 User manual

Quick Start for the HOBO® MX pH and Temperature Logger (MX2501)
22510-L MAN-MX2501-QSG
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.
1 Download and open HOBOconnect.
a. Download HOBOconnect® to a phone or tablet from the App Store® or Google Play™. Download HOBOconnect to a
Windows® computer from www.onsetcomp.com/products/software/hoboconnect.
b. Open HOBOconnect. If prompted, enable Bluetooth® in your device settings.
c. 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.
2 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.
a. 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.
b. 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.
c. Screw the closure cap onto the logger.
d. Use a squirt bottle to rinse the pH sensor with deionized
or distilled water.
e. Tap Devices (if necessary) and tap the logger tile in the
app to connect to the logger.
f. Tap Calibrate.
g. 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.
h. Rinse the pH sensor with deionized or distilled water.
i. 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.
j. Once the pH reading is stable, tap Confirm. Rinse the pH
sensor with deionized or distilled water.
k. If you are using the 10 buffer, place the sensor end in the
pH 10 solution and then tap Start. Once the pH reading is
stable, tap Confirm. If you are not using the pH 10 buffer,
tap Skip.
l. 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.
m. 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.
Unscrew the clear
cap filled with
storage solution
from the logger
Screw the closure
cap onto the logger
before calibrating
Closure cap
Sensor end cap Temperature sensor

© 2018–2022 Onset Computer Corporation. All rights reserved. Onset, HOBO, and HOBOconnect are registered
trademarks of Onset Computer Corporation. App Store is a service mark of Apple Inc. Google Play is a trademark of Google
LLC. Windows is a registered trademark of Microsoft Corporation. Bluetooth is a registered trademark of Bluetooth SIG,
Inc. All other trademarks are the property of their respective companies.
This product has been manufactured by Onset Computer Corporation and in compliance with Onset’s ISO 9001:2015
Quality Management System.
Patent #: 8,860,569 22510-L MAN-MX2501-QSG
3
Configure the logger.
a. 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).
b. Tap Configure & Start
c. 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.
d. 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.
4
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
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.
5
Download data from the logger.
a. Open HOBOconnect.
b. 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.
c. Tap Devices, connect to the logger, and then tap Download Data.
d. 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.
Copper guard
installed to
protect against
biofouling
Push the switch into the gap beneath the mounting
lanyard to start or stop logging or to wake up the logger.
Make sure the closure cap is installed
before deploying the logger