Overnight chlorine

skrause1

Member
May 2, 2012
7
Canton,IL
My pool has been clear since the beginning of the summer, however, this year it seems like I am losing more FC per day. My CYA is 40. I add enough chlorine to get to the top of the range, 7.0. Doesn’t matter if we get in it or not, when I test in the evening it is usually down to 3.0. It’s been costly adding so much every day. It has been sunny and in the upper 80’s low 90’s with little rain. I decided again to slam the pool since I had a CC of 1.0. Yesterday morning before light, I got a reading of 12.5. This morning another reading of 12.5. This is after leaving the pool at 14 just after dark both times. Is losing 1.5 ppm overnight not passing the overnight test? Is losing 4 ppm per day just due to sun normal?
Thanks so much!
 

duraleigh

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Apr 1, 2007
32,864
Sebring, Florida
It's more like you are losing around 2.0 ppm to the Sun and around 2.0 ppm to organics in your pool (Don't nit-pic that math, I am only generalizing :))

So I suggest you SLAM the pool. You must follow THIS article to the letter and I believe your FC consumption will drop in pretty short order,

Any visible "dust" on the floor? Is your water crystal clear or a b it hazy?
 

duraleigh

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No visible sign of algae, water clear......time to do the OCLT tonight and check your CC's when you do tomorrow's AM OCLT test.
 

mknauss

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TFP Expert
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May 3, 2014
22,761
Laughlin, NV
Once FC reaches 10 ppm, the pH test is valid (assuming you are using a proper test kit).

At that time, test the pH and adjust as necessary.