I have a autopilot dg220 with sc48 cell. Warning light flashing cell off needs 775 lbs salt. shows zero minerals. Pool salt is 2700 tested. My tri sensor is showing temperature and flow sensor working.I have cleaned in muratic acid and water has fixed temp and other warnings in the past. Is my tri sensor bad or do i have other problems. This morning all working fine my chlorine 3.5 PH 7.4 ta 100 ch 200 stabilizer 40.