I have a Hayward Pro-Logic system with salt etc. This is our 5th season. In May I took a water sample to my installation company and they suggested 8 oz. of BIO DEX Phosphate Remover Plus. Since then I've had nothin' but problems. Replaced the cartridges in the filter. Cleaned 'em again yesterday and the o-ring looks fine. Lubed and no leaks when i replaced the band. Replaced flow switch and test regularly with both strips and Taylor K-2006 kit. Everything checks out okay. Watched every video on the 'net and nothin' seems to help. My installer mentioned air might be gettin' sucked in somewhere. I purged air out of the tank and system light went off...for a day. An o-ring for the Tri Star strainer lid should arrive soon. If that doesn't work...?