I know this is old thread now but I appear to have finally fixed the issue. After battling this constant chlorine loss for weeks I called the pool company out. He was at a loss, he was impressed with the water balance the clarity and said the salt cell was good. He was baffled by the chlorine loss and agreed I should set way lower in percent. He said let’s test the phosphates just to see what they are. His kit ws bad so he sent me to the pool store, one store got 100ppb and another store got 350 neither felt the need to sell me anything. So again still lost. So I read everything on here read other articles in different places, kept going back to phosphates. So I emailed Hayward. Hayward says, we are confident your issue is phosphates or nitrogen/nitrates. So I decided to buy phosphate remover as I was aiming to go for a warranty claim so jump the hoops. Pool store recommended two 1lbs of cal-hypo., figured if I am going to sin might as well buy more stuff. So I treated phosphates, right about 24 almost 48 we were swimming and felt we smelled more chlorine than usual. I had already cleaned filter and removed some white particulate and drained out milky water from the filter tank. We sometimes would smell chlorine while on the deck and thought it was something with the splash out water, tests never showed any CC, just constant FC loss. So I decided to throw a bag of shock in FC went to 17ppm after an hour. Smelled a lot more chlorine. In the am about 12 hours after shock FC was 8., chlorine smell seemed gone water slightly cloudy. Cleaned filter again FC held at 8.5 all day and about 6:30 dropped to 6.5, non of these tests appeared to show any CC. I have now held 5-5.5 with swg set at 25 for 12 hours instead of 1.5-2.5 at 50 for 12 hours. Going to retest all levels tomorrow to see if all is in harmony finally. I have no idea what caused this issue but it was a PH battle then a chlorine battle and no signs of algae, no real smell that was a sign, no sign of CC being over 0.2. Two pool stores baffled, pool company baffled and I totally have no idea. My guess after tons of reading was either Hayward salt cells do not like phosphates at all or I had a balanced stalemate between ammonia and chlorine. Maybe lowering phosphates allowed chlorine to start working which unleashed the smell and then shocking kicked the build up out? Either way I don’t want to do this again and I hope it’s fixed.