EC-Salinity Probe Interface

Monitor hydroponic nutrient levels or salinity in aquariums, pools, and soil.

  • Electrical Conductivity in Siemens
  • Total Dissolved Solids in PPM
  • Salinity in PSU and PPT
  • Temperature in Celsius/Fahrenheit

ECSalinity probe

What it is

An I2C sensor device, an optional DS18B20 waterproof temperature sensor, and a two-electrode EC probe. It measures the conductivity of a solution and converts it into Siemens (S). From that value, it derives total dissolved solids and salinity. The firmware on the device provides two calibration options, single or dual point which can be used simultaneously. Temperature compensation is also provided in the firmware.

Using it

There is extensive documentation on the specifications, setup, and use of the device.

The library to use it is in the Arduino and IDE. A python and rust implementation for Raspberry Pi is available. There are also MicroPython and Espruino javascript libraries.


#include <ECSalinity.h>
EC_Salinity ec;



extern crate ufire_ec;
use ufire_ec::*;
let mut ec = EcProbe::new("/dev/i2c-3", 0x3c);

let ms = ec.measure_ec(0.019);


from ecsalinity import ecsalinity
ec = ecsalinity(3)

Probe Selection

Any 2-electrode probe can be attached to the device. EC probes are specified by their cell constant (K).

A probe with a K constant of:

A BNC connector comes standard, but the board can be ordered without it.

Buy it

The board can be purchased by itself, conductivity probes are also available separately. Buy the board and a probe and get the I2C Sensor Isolator board for 20% off. The discount will be automatically applied.

EC-Salinity Probe Interface

The board by itself.

Conductivity Probe

Black platinized in 1K or 10K with a BNC connector.

Support and Questions

If you have questions, find a bug, or have any suggestions, go to this project’s GitHub page and submit an Issue or Pull Request. Or you can send an email to [email protected].

Source code and schematics are open and MIT/CERN OHL licensed.

Contact us, newsletter, and store policies