Just got back from Leslies water testing. The water is balanced, as far as PH, alk, CYA etc....he said that it's called Chlorine Breakpoint, where sometimes you can have more nitrates and phosphates??? and that the pool could have just been dirtier than in the past (though it was clear)...and that I just have to add 2 one-pound packages of Power Powder Plus (its fast-dissolving shock treatment and superchlorinator..73% calcium hypochlorite)--....wait 4 hours and then test...if still no chlorine registering...do same again ...wait 4 hours, test, etc...then once the level is where I want it to use just one 1lb package per week. (seems like alot cause the one-pound bag treats 16, 500 gallons and we only have a 9,000 gallon pool)....but here it goes....