Why does the controller permanently indicate a too high/low pH value? And why doesn’t the calibration work although the sensor is new?
The cause can probably be fixed quite easily. The protective cap of the pH sensor needs to be removed before insertion into the aquarium / before the calibration, to carry out control/calibration correctly. The protective cap serves as storage and “reactivation” of the sensor with the storage liquid. It has to be removed for use inside the aquarium and during the calibration because no water from outside can pass through. If the controller still displays an error, even after the removal of the protective cap, please read the FAQ with the several error messages in detail.