okay so does anybody know anything about fertilizer being in pool water and making it impossible to get a chlorine reading? I have dumped about 10 gallons of shock into my pool not to mention probably 10 bags of shock prior to that. the guy that opens and closes my pool is telling me my pool is loaded with fertilizer but when I asked how he knows that he doesn't tell me he does not use test kits either.Good to know that. My pump runs 24/7 so that will make it easier to get a water sample.