Onset HOBO MX2501 pH and Temperature Data Logger

The HOBO MX2501 pH and Temperature Data Logger is designed for long-term monitoring of pH in estuaries, lakes, streams, rivers, and oceans. Leveraging Bluetooth Low Energy® (BLE) technology, the MX250

  • Product Name:Onset HOBO MX2501 pH and Temperature Data Logger
  • Model:MX2501
  • Maunufactor:Onset
  • Country:USA

The HOBO MX2501 pH and Temperature Data Logger is designed for long-term monitoring of pH in estuaries, lakes, streams, rivers, and oceans. Leveraging Bluetooth Low Energy® (BLE) technology, the MX2501 pH Logger communicates wirelessly with the free HOBOconnect app and your mobile device, making logger setup, calibration, and data offload quick and easy. A guided pH calibration process on the HOBOconnect app makes an otherwise complicated process easier to follow. This affordable and compact logger dramatically cuts the time and effort needed to collect field data, while also offering higher resolution data. (NOTE: pH electrodes should always be stored in storage solution when not deployed.)

Highlighted Features 
  • Guided pH calibration following on-screen prompts in HOBOconnect app

  • Rugged PVC housing for deployment in both freshwater and saltwater environments

  • Quick and easy data offload via Bluetooth Low Energy (BLE) to iOS and Android devices

  • Water detection system for longer battery life and less maintenance

  • Potentiometric pH electrode with plastic body, gel electrolyte, and double cloth junction

  • User-replaceable battery, pH electrode, and anti-biofouling copper guard

  • Accuracy of ±0.10 pH units within ±10°C of temperature at calibration


pH Sensor

pHmV
Range2.00 to 12.00 pH-512 to 512 mV
Accuracy±0.10 pH units within ±10°C of temperature at calibration±0.20 mV
Resolution0.01 pH0.02 mV
Response Time1 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)
Resolution0.024°C at 25°C (0.04°F at 77°F)
Response Time7 minutes typical to 90% in stirred water
Logger
Operating Range-2° to 50°C (28.4° to 122°F) — non-freezing
BuoyancyFresh water: 13.6 g (0.48 oz) negative
Salt water: 19.6 g (0.69 oz) negative
WaterproofTo 40 m (131.2 ft)
Water DetectionWater 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 Power1 mW (0 dBm)
Transmission RangeApproximately 30.5 m (100 ft) line-of-sight in air
Wireless Data StandardBluetooth Low Energy (Bluetooth Smart)
Logging Rate1 second to 18 hours
Logging ModesFixed interval (normal, statistics) or burst
Memory ModesWrap when full or stop when full
Start ModesImmediate, push button, date & time, or next interval
Stop ModesWhen memory is full, push button, date & time, or after a set logging period
Time Accuracy±1 minute per month 0° to 50°C (32° to 122°F)
Battery TypeOne AA 1.5 Volt, user-replaceable
Battery Life1 year typical at 25°C (77°F) with logging interval of 1 minute and Bluetooth Always On selected in software.
2 years typical at 25°C (77°F) with logging interval of 1 minute and Bluetooth Off Water Detect enabled in software.
3 years typical at 25°C (77°F) with logging interval of 1 minute and Bluetooth Always Off selected in software.
Faster logging intervals and statistics sampling intervals, burst logging, remaining connected with the app, excessive downloads, and paging may impact battery life.
pH Electrode Typical Minimum Life6 months in sample with ionic strength ≥ 100 µS/cm
Memory152 KB (43,300 measurements, maximum)
Full Memory Download TimeApproximately 60 seconds; may take longer the farther the mobile device is from the logger
Dimensions22.86 x 4.27 cm (9.0 x 1.68 inches); mounting hole 0.64 cm (0.25 inches)
Weight268.2 g (9.46 oz)
Wetted MaterialsLogger: PVC housing and sensor end cap, polycarbonate closure caps and mounting end cap with a TPE switch
pH electrode: plastic-bodied with Pellon® junctions and gel electrolyte, glass pH sensor bulb
Environmental RatingIP68
CE CompliantThe CE Marking identifies this product as complying with all relevant directives in the European Union (EU).