Lowering CYA by draining in a Liquid Chlorine pool

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S

skrichard

0
Jun 9, 2010
21
Indianapolis, IN
Pool Size
23000
Surface
Vinyl
Chlorine
Liquid Chlorine
Tried searching threads but really didn't see/find my question/answer.
I have a 23k gal vinyl free form pool, gas heater, Hayward pump. I use liquid chlorine, and rarely have to do anything else other than a little acid if pH starts rising. It has never been higher than 7.9. Hovers about 7.4 ish.

However over the course of the last 2 months my CYA has been steadily rising and I don't use tabs so why and where is it coming from? I have TFP kit and will also run a sample to the pool store to see how far off I am with my results.

I have drained water down to past skimmer door (opening drain line on the cartidge filter) and refilled with city water via hose. 2 x since June, but I don't see CYA dropping. What am I not doing or doing wrong?

Here are a few sample readings

Opening 4/14/23
FC 10.49*
TC 11.67*
* this is high due to initial shock of adding 5-6 gal liq Chlorine. Pool guy starts season by filling Rainbow feeder with pucks.
I NEVER REFILL IT AT ALL DURING THE SEASON!
CYA 37

5/5/23
FC 1.78
TC 1.93
CYA 59*

5/31/23
FC2.71
TC 2.99
CYA 81

6/23/23
FC 1.93
TC 2.18
CYA 92

7/6/23
FC 8.49*
TC 8.49*
I had added liquid and shocked due to all the grandkids in pool on 7/5
CYA 89

7/16/23
FC 1.24
TC 1.44
CYA 101
 
skrichard said:
Tried searching threads but really didn't see/find my question/answer.
I have a 23k gal vinyl free form pool, gas heater, Hayward pump. I use liquid chlorine, and rarely have to do anything else other than a little acid if pH starts rising. It has never been higher than 7.9. Hovers about 7.4 ish.

However over the course of the last 2 months my CYA has been steadily rising and I don't use tabs so why and where is it coming from? I have TFP kit and will also run a sample to the pool store to see how far off I am with my results.

I have drained water down to past skimmer door (opening drain line on the cartidge filter) and refilled with city water via hose. 2 x since June, but I don't see CYA dropping. What am I not doing or doing wrong?

Here are a few sample readings

Opening 4/14/23
FC 10.49*
TC 11.67*
* this is high due to initial shock of adding 5-6 gal liq Chlorine. Pool guy starts season by filling Rainbow feeder with pucks.
I NEVER REFILL IT AT ALL DURING THE SEASON!
CYA 37

5/5/23
FC 1.78
TC 1.93
CYA 59*

5/31/23
FC2.71
TC 2.99
CYA 81

6/23/23
FC 1.93
TC 2.18
CYA 92

7/6/23
FC 8.49*
TC 8.49*
I had added liquid and shocked due to all the grandkids in pool on 7/5
CYA 89

7/16/23
FC 1.24
TC 1.44
CYA 101
Click to expand...
Pool store results can be wildly inaccurate
You need to test with your own accurate test kit & post those results.

You mentioned “shock” & liquid chlorine.
What “shock” products are you using.
Dichlor & Trichlor increase cya.
Does the pool guy just open the pool or does he visit regularly?
Cya only increases by adding cya containing products.
 
I would be willing to bet the "experts" at the pool store also recommended purchasing products with their free testing. Have you bought anything from them this swim season?

Phosphate remover, algaecide, clarifier, and cool sounding magic potions like "Green to clean" or "Perfect pool weekly" are some of their favorite money makers.
Heck, before we even had a pool, I had to run into leslies and let one of the kids use their restroom. They sold me some kid safe phosphate remover. The kids said it tasted horrible, but I told them to listen to the experts.
 
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