Gikfun 2PCS TDS Sensor Water Conductivity Meter, 0-1000ppm Analog Output Sensor Module with Waterproof Probe, Compatible with Arduino for Hydroponics, Labs, Water Quality Testing EK2169

Wide Voltage Input: 3.3V to 5.5V
Working Current: 3 ~ 6mA, TDS Measurement Range: 0 ~ 1000ppm
Good Compatibility Output: 0 to 2.3V analog signal output, compatible with 5V or 3.3V controller.AC Excitation Source, effectively prevent probe from polarization
Easy to Use: Arduino compatible, simple connection, plug and play without soldering. You can build a TDS detector easily to measure the TDS value of liquid
It can be used in water quality application, such as domestic water, hydroponics. So you can easily DIY water purity tester