Electrical conductivity meter

[1] It has multiple applications in research and engineering, with common usage in hydroponics, aquaculture, aquaponics, and freshwater systems to monitor the amount of nutrients, salts or impurities in the water.

Common laboratory conductivity meters employ a potentiometric method and four electrodes.

Industrial conductivity probes often employ an inductive method, which has the advantage that the fluid does not wet the electrical parts of the sensor.

The liquid passing through a channel in the sensor forms one turn in the secondary winding of the transformer.

A benefit of four-electrode conductivity sensors compared to inductive sensors is scaling compensation[clarification needed] and the ability to measure low (below 100 μS/cm) conductivities (a feature especially important when measuring near-100% hydrofluoric acid).

[citation needed] Kraft pulp mills use conductivity-based concentration measurement to control alkali additions to various stages of the cook.

The scaling on the electrodes needs to be taken into account, otherwise the conductivity measurement drifts, requiring increased calibration and maintenance.