HOBO® MX pH and Temperature Logger (MX2501) Manual
HOBO MX pH and
Temperature Logger
MX2501
Included Items:
• pH electrode installed and
submerged in storage
solution
• Extra electrode storage
solution
• Anti-biofouling copper guard
• Silicone-based O-ring grease
and foam swab
Required Items:
• HOBOconnect app
• Mobile device with
Bluetooth and iOS, iPadOS®,
or Android™, or a Windows
computer with a native BLE
adapter or supported BLE
dongle
• Deionized or distilled water
and squirt bottle
• Calibration solutions
Accessories:
• Replacement pH electrode
(MX2500-ELECTRODE)
• Calibration kit with three
bottles: pH 4.01, 7.00, and
10.00 calibration solution
(MX2500-CAL-KIT) and
calibration beakers
(MX2500-CAL-BKR)
• Maintenance kit with
calibration kit plus storage
solution (MX2500-MAINT-
KIT)
• pH 4.01 calibration solution
(MX2500-CAL-4)
• pH 7.00 calibration solution
(MX2500-CAL-7)
• pH 10.00 calibration solution
(MX2500-CAL-10)
• Electrode storage solution
(MX2500-STORE-SOLN)
• Replacement sensor end cap
(MX2500-END-CAP)
• Replacement anti-biofouling
copper guard (MX2500-
GUARD)
• Replacement clear storage
cap (MX2500-STORAGE-CAP)
22511-Q
The HOBO MX pH and Temperature logger is designed for long-term monitoring of pH in
aquatic systems. With a replaceable pH electrode and anti-biofouling copper guard, this
durable logger can be deployed in both fresh and salt water environments. This logger is
Bluetooth® Low Energy (BLE)-enabled for wireless communication with a mobile device or
computer. Using the HOBOconnect® app, you can easily calibrate and configure the logger,
download logged data to your phone, tablet, or computer, or automatically upload the data to
HOBOlink® for further analysis. You can also configure the logger to calculate statistics, set up
alarms to trip at specific thresholds, or enable burst logging in which sensor readings are logged
at a faster interval when the pH or temperature rises above or falls below certain limits.
Specifications
pH Sensor
Range
Accuracy
Resolution
Response Time
Sample Ionic Strength
Temperature Sensor
Range
Accuracy
Resolution
Response Time
Logger
Operating Range
Buoyancy
Waterproof
Water Detection
Radio Power
Transmission Range
Wireless Data Standard
Logging Rate
Logging Modes
Memory Modes
Start Modes
Stop Modes
Time Accuracy
Battery Type
in pH
2.00 to 12.00 pH
±0.10 pH units within ±10°C of
temperature at calibration
0.01 pH
1 minute typical to 90% at constant temperature in stirred water
≥ 100 µS/cm
-2° to 50°C (28.4° to 122°F)
±0.2°C (±0.36°F)
0.024°C at 25°C (0.04°F at 77°F)
7 minutes typical to 90% in stirred water
-2° to 50°C (28.4° to 122°F) — non-freezing
Fresh water: 13.6 g (0.48 oz) negative
Salt water: 19.6 g (0.69 oz) negative
To 40 m (131.2 ft)
Water conductivity level of 100 µS/cm or greater is necessary for
reliable detection of water. Deionized water or water below 100 µS/cm
may not be detected.
The water conductivity circuit may not reliably detect water that has
frozen around the electrodes, i.e. below 0°C (32°F).
1 mW (0 dBm)
Approximately 30.5 m (100 ft) line-of-sight in air
Bluetooth Low Energy (Bluetooth Smart)
1 second to 18 hours
Fixed Interval or Burst
Never Stop (Overwrites Old Data) or Stop When Full
On Save (immediate), On Next Interval, On Push Button, On Date/Time
Never Stop (Overwrites Old Data), On Date/Time, After a specified
about of time, Stop When Memory Fills
±1 minute per month 0° to 50°C (32° to 122°F)
One AA 1.5 Volt, user-replaceable
in mV
-512 to 512 mV
±0.20 mV
0.02 mV
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