HOBO® MX pH and Temperature Logger (MX2501) Manual
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
in
pH
in mV
Range
2.00 to 12.00 pH
-512 to 512 mV
Accuracy
±0.10 pH units within ±10°C of
temperature at calibration
±0.20 mV
Resolution
0.01 pH
0.02 mV
Response Time
1 minute typical to 90% at constant temperature in stirred water
Sample Ionic Strength
≥
100 µS/cm
Temperature Sensor
Range
-2° to 50°C (28.4° to 122°F)
Accuracy
±0.2°C (±0.36°F)
Resolution
0.024°C at 25°C (0.04°F at 77°F)
Response Time
7 minutes typical to 90% in stirred water
Logger
Operating Range
-2° to 50°C (28.4° to 122°F) — non-freezing
Buoyancy
Fresh water: 13.6 g (0.48 oz) negative
Salt water: 19.6 g (0.69 oz) negative
Waterproof
To 40 m (131.2 ft)
Water Detection
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).
Radio Power
1 mW (0 dBm)
Transmission Range
Approximately 30.5 m (100 ft) line-of-sight in air
Wireless Data Standard
Bluetooth Low Energy (Bluetooth Smart)
Logging Rate
1 second to 18 hours
Logging Modes
Fixed Interval or Burst
Memory Modes
Never Stop (Overwrites Old Data) or Stop When Full
Start Modes
On Save (immediate), On Next Interval, On Push Button, On Date/Time
Stop Modes
Never Stop (Overwrites Old Data), On Date/Time, After a specified
about of time, Stop When Memory Fills
Time Accuracy
±1 minute per month 0° to 50°C (32° to 122°F)
Battery Type
One AA 1.5 Volt, user-replaceable
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)
