CYA decreasing

lucyyan

Member
Jul 14, 2023
15
Winnipeg Manitoba
opened our pool in May and CYA measured 50
two days ago I measured again with the Taylor test kit and it was below 30 (not sure how low as the test tube only shows to 30)
Chlorine was very low so at night I added almost 8L of 10.3% chlorine, measured again in an hour and FC was 6, CC zero
TA 110, pH was high, test only shows to 8 but I think it might be slightly higher than that

At 730am the next day FC was 5, CC0, TA110, CYA still below 30 i suspect, I added acid in to try and reduce the pH I think now its at 7.8 ish

I did end up going to a pool place because I know their CYA tube can measure till 20 and they could still see the black dot at 20 so it must be pretty low

When I got home around 5pm FC was 1.5 but it was very humid and hot today (30degrees with high humidity)

so im guessing I still have stabilizer cuz its still holding chlrorine? it doesn't seem that crazy to have lost 3.5 in 10 hours on a hot humid day?

what would cause CYA to go down, we didn't drain, there wasn't that much splash out , i don't think there is a leak we haven;t need to fill the pool very much. From what I read you can loose CYA and produce ammonia but CC would be very high which I am not getting

What would be my next step? I am paranoid about having too much CYA (last year we had to drain most of our pool due to high CYA this was before I found TFP). pool is crystal clear at this point.
 
so im guessing I still have stabilizer cuz its still holding chlrorine?
Likely some.
it doesn't seem that crazy to have lost 3.5 in 10 hours on a hot humid day?
No, not in the heat of summer and low CYA. Very normal.

what would cause CYA to go down,
CYA degrades between 5-15 per month, depending on conditions. In summer I test CYA weekly, every other week in the shoulder months.

Raise your CYA back to 50. Then chlorinate by following this...Link-->FC/CYA Levels
 
Likely some.

No, not in the heat of summer and low CYA. Very normal.


CYA degrades between 5-15 per month, depending on conditions. In summer I test CYA weekly, every other week in the shoulder months.

Raise your CYA back to 50. Then chlorinate by following this...Link-->FC/CYA Levels
how do you know how much to put in to get to 50? I don't know what I am starting with. just add a little bit every few days till I get to 50?
 
I measured again with the Taylor test kit and it was below 30

how do you know how much to put in to get to 50? I don't know what I am starting with. just add a little bit every few days till I get to 50?
Add 20ppm. Test 48 hours later. Adjust again based on that 48 hours later test.
 
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