ok, working on it. been keeping it => 15ppm. Does it matter whether I use the powdered shock or liquid bleach - or more directly - is one more succeptible to burn off from the sun? I'm told that during the day it may burn off, but also that I am not supposed to use my solar cover because the elevated levels of chlorine could ruin it. Is the buffered shock more likely to keep FC levels elevated during the day? or doesn't it matter. Many thanks by the way.