• pH calibration
  • Rugged PVC housing
  • Measuring range:
    • 2 to 12 pH range
    • 28.4 to 122°F (-2 to 50°C)
  • Bluetooth Low Energy (BLE) to iOS devices
  • Water detection system for longer battery life
  • 152 KB memory (43,300 measurements)
  • Waterproof up to 131.2ft (40m)
  • Potentiometric pH electrode

What's in the Box

  • pH Electrode
  • Storage solution
  • Anti-biofouling copper guard
  • Tube of silicone grease
  • AA battery


The HOBO MX2501 pH and Temperature Data Loggers are designed for long-term monitoring of pH in both freshwater and saltwater environments. The MX2501 features Bluetooth Low Energy® (BLE) technology. The pH Logger communicates wirelessly with the free HOBOmobile® app on iOS devices making logger setup, calibration, and data offload quick and easy. A guided pH calibration process on the HOBOmobile 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 in data.