My Tunze is acting up, I think it's the eye maybe needs to be cleaned ? It starts filling up so the alarm goes off because there is to much water in the sump anyone have issues with these ?
You do need to clean the sensor from time to time. Espeically before going away for a couple days, check and test the sensor and clean it if necessary. The salt and mineral can dry up on the sensor.
The controller is very sensitive to electronic near by. Try to relocate the controller if cleaning the sensor doesn't work.
If it is under warranty, Roger from Reefcentral (Tunze USA) is very helpful.