Hi. I'm fairly new to the forum. Opened my pool for the first time this year following TFP advice and got it from green to clean in a week and never went to the pool store. It's been crystal clear in the weeks since, even despite the never ending rain here in Indiana. Now that we finally have a few sunny days in the forecast I decided to put the solar cover on to help with the chlorine burnoff. Pool gets full sun all day long. CYA was at 50 but with all the rain it may have come down. I haven't retested in a while. Anyway, before putting the solar cover on FC was at 2 (I know, too low, but the sun zapped it), CC at 0.5. I put in 6 cups of bleach to get it back to 8, (1 cup equals roughly 1ppm in my 5,300 gallon pool) then put the solar cover on for the first time this year. Let the pump run all night just in case there were nasties on the cover. This evening after running the pump for a couple hours I tested FC again and it was off the charts. I got to 30 before I quit. Tried again just in case I made a mistake and got over 20 before I quit again. What on earth would cause such a thing? I'm using the Taylor 2006 kit with TFP refills. BTW pH is 7.5 and steady, TA is around 140. Ideas?