Chlorine Problems

[acmtn]

Switched my pool (20,000 gal.) recently from Pristene Blue to the BBB method. I am having problems getting my FC up. Just yesterday I put in 2 gal. of bleach and 1 lb. of clorinated shock. This morning my FC level is 0.5. Other readings are: PH 7.0, alkalinity is 120, cya is approx. 100.

What do I need to do to get my FC level up and what level should I be at? Thanks in advance for any help.

[duraleigh]

Chlorine is constantly consumed from the 1)Sun and from 2)organics entering your pool. If you are losing more than 2-3ppm daily (and you are), you are consuming chlorine because you have organics (probably algae) in your pool.

You need to shock by adding enough chlorine to get to 25ppm if it's a vinyl pool and 30-35 would be better if your pool is gunite. Keep the Cl AT THAT LEVEL UNTIL YOU HAVE NO CL LOSS OVERNIGHT (2ppm or less). Now the organics (and chloramines) are cleared from your pool and you can let your Cl level drift down into an 8-15ppm range and keep it there the rest of the Summer. Expect to lose somewhere around 2ppm daily because of the Sun.

Download bleachcalc to calc how much Clorox you need to do that....it'll be more than you think.

[acmtn]

I realize that I may be fighting something in my pool but my pool is sparkling clear. Could I have algae present and my pool really look as good as it does?

[JohnT]

I realize that I may be fighting something in my pool but my pool is sparkling clear. Could I have algae present and my pool really look as good as it does?

Could be any other biological contaminant. Heavy swimmer load or young swimmers (urine and sweat).