Yesterday I had a low salt reading and purifier was off on my Pool Pilot. I had just tested the salt 2 days before with a Taylor drop kit and it was 3600. Calibration setting was 1900. I increased this to 2900 (highest it would allow me to go). Later, I decided to clean cell as I had never done this and pool is 3 years old. Cell looked clean but I went ahead, cleaned it and reinstalled. When I turned power back on calibration was off again and I was able to reset it exactly to amount tested (I was not limited to 1000ppm limit for some reason). Today after work I go check on it and sure enough, low salt, purifier not running. Check calibration and it is at 2200. I tested salt again and get 3400. I reset calibration again. What could make the unit change calibration settings? Power interruption? The power has gone off before and never had issues.