all of my levels are right on the money according to the pool school..My only question is once you do the overnight test and your chlorine starts holding then how do you get it to drop back down.. my cya level is right so the sun isnt taking it down.. and there is no organics so im not losing anything there.I know this is a good problem to have and im sure there is a simple answer.My chlorine is holding now at about 19 and i want it to be about 4 or 5