Fighting Something. . .

Ok - I seem to be fighting something, and just wanted some advice. I've been doing the pool thing for a while (5 years) and I'm using Bleach at the current time.

I have an 18X36 IG Vinyl ~22,000 gallon pool.

Last night I put in 3 3/4 gallon bottles of 6% bleach. This should have given me 6 ppm of Cl to the pool.

Here are my readings after adding Cl last night:

FC-6.5
CC-0
TC-6.5
pH-7.5
ALK-120
CYA-30

This morning - I tested the water at 9:30am, just as the sun started coming up over the trees in the back yard.

FC-1.0
CC-0
TC-6.5
pH-7.5
ALK120
CYA-30

I'm a little frustrated due to the fact that my Cl keeps dropping like crazy, but I never have any CC.

Should I be following the 'Best Guess CYA' shock chart? 15ppm seems really really high to me, but shocking ot 6 and 8 ppm over night hasn't been working.

Yes. Follow the CYA best guess table. Shock to 15 and keep it there for a day or two. If that doesn't fix the problem I suggest you raise CYA to 40 and try it there. If it STILL doesn't hold better, go to 50 on CYA and keep your FC at the higher end of the 3-5 range.

You may have to do both. When summer gets really blistering (like now) I raise CYA to 40 so chlorine stays in longer--and run higher FC residual levels.

Thanks for the quick reply Carl.

I'll be going to 15ppm tonight, but unfortunately won't be able to be around to try to maintain it for a few days, so I'll be putting pucks in the feeder before I leave tomorrow morning.

I'll see how things look when I get back in town - hopefully not cloudy.