Disappearing CYA

[JenLar]

Hi all,

I just had to post what happened with my pool this week. On Monday I put 2 gallons of liquid chlorine in, bringing the FC level up to 4ppm. I didn't test on Tuesday.

On Wednesday, I felt some slime growing on the pool wall, so I tested, and got 0 FC.

I couldn't figure out how it dropped that fast, so I did the CYA test, which also registered 0.

Suspecting user error, I got a fresh water sample and repeated the test. The results were the same.

I repeated the process 2 more times, with the same results.

At that point I decided to walk away for a while, and test my sanity by doing some laundry.

The laundry came out fine, so I decided to get an outside opinion. The result of the pool store test? 0 CYA! as well as 0 FC, of course.

There must be some bacteria that ate up all my CYA!

"It's the end of the world as we know it...."

 

[mknauss]

Hard to imagine it happened that fast -- but -- try this

Do not add any more CYA.

Add enough chlorine to the pool to get FC 10. Circulate for 15 minutes. Test, if FC is 6 or less, add enough chlorine to get back to 10 and repeat. Once your chlorine holds between 7 and 10 ppm, you have consumed the ammonia and can add CYA and move on to a SLAM.

Take care.

 

[Catanzaro]

Below is some information on some old threads that explains what could have happened in detail.

There is a relationship between bacteria and CYA, and its conversion to ammonia. You will need to SLAM until you hold chlorine and then add the CYA accordingly to get back up to where you need to be.


CYA disappeared? Is that even possible?

It Can Happen to Anyone - Zero Chlorine, CYA--Ammonia

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Please follow mknauss advice on chlorine additions.