Review on High-Quality Replacement BNC Electrode Probe Connector Cable Sensor for pH Controller Monitor Tester Meter Kit Set - Ideal for Seawater, Saltwater, Hydroponics, Aquarium, Plant, Pool, and Spa with 0-14 pH Range by Djuan Thompson

Arrived, tests showed that the calibration is unstable. Changes over time for an unknown reason. Make sure you calibrate when the device is at room temperature. The room temperature should be close to the normal daily temperature and increase if necessary. I tried minimizing the high-low edge and center to minimize skew. Has been connected to a backup battery with surge protection. Suspicious tolerances of internal components make the device prone to drift. I have endeavored to eliminate earth currents etc.