Where did my CYA go?

[iggy]

My SWG inground 12,000 gallon pool was completed in January this year. We had the CYA up to 100 ppm and all of a sudden in June the CYA tested 50 ppm on both liquid test and strips and has been that way every since. I want to maintain 80 ppm and know I need about 3 lbs of CYA to get up again to 80 ppm.

My question where di my CYA go?
I thought it doesn't evaporate.
I have cleaned my filters 3 times since filling in Janauary and have only drained the pool about 2" because of rain.
Could these things together reduced my CYA 50%?

 

[frustratedpoolmom]

Do you have an autofill feature?

 

[frustratedpoolmom]

It doesn't evaporate. 2 inches of water - that's not that much certainly not enought reduce by half.

 

[Butterfly]

iggy,

When did your CYA last test at 100 and what method did you use to test?

 

[iggy]

Do you have an autofill feature?

Yes I have the automatic fill feature.

 

[iggy]

iggy,

When did your CYA last test at 100 and what method did you use to test?

Around June 20th

 

[rimshaker]

My CYA disappeared since last summer also; down from 100+ to only 40 last week.

Old fashioned pool with no automatic drainage or backwash. Nothing but rainwater, fill water, and evaporation cycles all year.

Winters are very mild in FL; and no algae blooms since last year... so how do I account for CYA loss?

 

[frustratedpoolmom]

Do you have an autofill feature?

Yes I have the automatic fill feature.

You may have a slow leak....if your autofill feature is running and replacing water you could have replaced more than 2 inches....

 

[iggy]

Do you have an autofill feature?

Yes I have the automatic fill feature.

You may have a slow leak....if your autofill feature is running and replacing water you could have replaced more than 2 inches....

I'm 99.9% sure I do not have any leaks.

 

[frustratedpoolmom]

I'm 99.9% sure I do not have any leaks.

Because? :?:

 

[chem geek]

Going from a CYA level of 100 on June 20th (I assume this year) to 50 on July 11th in a pool with chlorine (maintaned FC level) in it seems impossible without dilution or some sort of test error. Such drops have been seen over a winter in pools that have been "let go" (presence of algae is not needed; it's soil bacteria that typically convert CYA into ammonia). So we've got a mystery here.

If there were some sort of leak, then other water parameters would likely drop unless the fill water was high in such parameters. Calcium Hardness, for example.

Richard

 

[iggy]

Going from a CYA level of 100 on June 20th (I assume this year) to 50 on July 11th in a pool with chlorine (maintaned FC level) in it seems impossible without dilution or some sort of test error. Such drops have been seen over a winter in pools that have been "let go" (presence of algae is not needed; it's soil bacteria that typically convert CYA into ammonia). So we've got a mystery here.
If there were some sort of leak, then other water parameters would likely drop unless the fill water was high in such parameters. Calcium Hardness, for example.

Richard

I'm still scratching my head on this one. I usually test weekly after the pool was filled then every two weeks. I did most of thests but followed up at Leslie Pool store which usually validated my reading. I have a feeling I will just have to leave this as unsolved and just add my my 3 lbs of CYA and move on.

Thanks everyone.