I am a new member and very glad to have found TFP. For years I have just listened to the people at the pool stores with much confusion. My Taylor test kit is a beautiful thing. I just shut my SWG off a couple days ago. I have had metal corrosion, light blue scale in my cleaner filter bag, metal stains on my liner and insufficient chlorine output even running it at 100% for 12 hours/day. The unit says low/add salt but I checked it and it was 3470. I tried adding 1 bag of salt which took the reading to 3770 with the unit still reading add salt. I have talked to the distributor about the unit and they have told me to check my water for excessive phosphate levels and cannot explain the low salt reading. They said I may need to replace the cell. I'm tired of trying to keep my pool under control using it. I am now using Calcium Hypochlorite unstabilized tablets and granular when I need it and to shock. Since I have switched back I have had to backwash my filter every couple days. Is this related to my switch? My FC is 3-4, Ph 7.5-7.6, TA 100, CH 220-230 and CYA 60. The water is clear. I shock and add some algaecide once a week. I treated the stains with ascorbic acid and have been using a sequestering agent weekly but the stains have returned. Any input would be appreciated.