I am a new to TFP. I need help I have been battling with algea for a week now. taken sample of water to a place that I been going to for past 5 yrs (they been really good). I have put in 48# chlorine, qt. black algeacide, qt. murtice acide, and running the pump 24/7 all the level is good except for the cyn which is at 20. We live in Ok where it is hot this week the temp is above 90 degree I have put the chlorine in the evening every 12 hrs. The pool is 25,000 gal inground vinyl pool, sand fliter, pump is 1.5 hp. I have thinking that the cyn is low that it is not holding the fc to kill the algea. I am at my wits end please help. I don't want to drain the pool but if I have too I will.