Specializing In 4-20 mA Water Quality Sensors

Simplify your measurements with durable, accurate, and user-friendly water quality sensors.

All sensors are fully submersible, electrically isolated, and designed to last 10+ years.  They incorporate numerous features to avoid headaches such as ground loops and background noise.  All dataloggers, PLCs, and SCADA systems that accept analog inputs are compatible.


Which pHionics Sensor Series Is Best For Your Application?

The D-phi Series™

Recommended for recirculating aquaculture systems, process control, hydroponics, and wastewater applications.


Click for more information


  • Refillable differential electrode
  • Built-in pipe mounting threads
  • 1″ diameter
  • Titanium and Delrin® housing

Starting at $549 USD

Inline and submersion models available

The STs Series™

Recommended for remote, long-term monitoring applications and narrow pipe/well measurements.


Click for more information



  • Field-replaceable electrode
  • Built-in 0-50°C temperature sensor
  • 0.75″ diameter
  • 316 Stainless Steel and Kynar® housing

Starting at $930 USD


Autonomous Data Collection

Easily collect large amounts of accurate water quality data around the world by connecting pHionics sensors with remote telemetry units.

Groundwater Monitoring

Take early action on changes in groundwater quality to protect crops or prevent harmful agricultural runoff from damaging local waterways.

Aquaculture Automation

Maximize fish size and reproduction rate by connecting pHionics sensors with SCADA or PLC systems to maintain optimal water conditions.

…and many more!

Or enhance your knowledge through our

Featured Article

The Guide to pH Drift

 pH drift is one of the most frustrating issues to troubleshoot because it can seem random and be caused by many different aspects of the environment, maintenance, and sensor design.  This guide provides steps to simplify the troubleshooting process and determine what the cause of drift is along with how to fix it.

Read more…