Hamilton Conducell 2-pole and 4-pole conductivity sensors rely on metal electrodes to measure the conductivity of the liquid. Coatings, scale, and particulate build-up from the process can obscure the electrode reducing the accuracy of the measurement. This coating should be removed for best results.
The tip of a Conducell 4USF Sensor can be seen here. 4-pole conductivity sensors can compensate for some build-up on the electrodes but periodic inspection and cleaning ensures the best performance.
Visually inspect the metallic electrodes of the sensor for coating. Simple soap and water (Alconox) are effective cleaners for soft coatings and particulates. Alcohol is also a suitable cleaner if oils or fats are present. If cleaning a 2-pole sensor such as the Conducell UPW then it may be necessary to spray water into the hollow areas at the tip of the sensor to dislodge materials. Avoid abrasive scrubbing of the surface which may scratch or damage the electrodes.