Newbie CYA question

[pooldummy]

Is cyanuric acid (CYA) only reduced through the removal/replacement of pool water, or does it break down or decay naturally over time (e.g. during the months the pool is closed)?

My lame test strips (a real test kit is still on its way to me) indicate I probably have a CYA level of at least 100. After years of dichlor and trichlor abuse, I'm surprised it's not higher. Who knows, it may well be once I can do a real test. Anyhow I plan to do a partial drain/refill but don't want to take the water level down more than 1 foot at a time (vinyl liner), and probably don't have the time to do more than 2 intentional drain/refills this season. And of course there will be some removal/replacement due to backwashing, vacuuming, etc. But I was curious if CYA breaks down on its own over a lengthy amount of time.

 

[lovingHDTV]

Typically you have to replace the water to get rid of CYA. There have been reports of CYA breaking down during the off season or when FC goes to 0.

It has happened to me a few times, but it is not the "norm". You will need to replace some water to lower it.

If you are seeing 100+ be sure to do a test where you dilute the water to get a better reading as to the true CYA value.

If you dilute it with non-CYA containing water 50-50, then you can 2x the results and error.

dave

 

[PaulR]

There have been reports that soil bacteria in a pool with FC 0 will consume CYA and produce ammonia. You then spend big bucks dumping in chlorine to get rid of the ammonia. In most cases it is cheaper to replace the water.
--paulr

 

[Water_man]

In my area three pools, including mine, lost their CYA during the winter closing season. No ammonia was found. All we did was adding CYA and continued with the "program".

 

[frustratedpoolmom]

No one really knows why some pools have unexplained loss of CYA and others don't. Conversion to ammonia is found in some cases but not all. Still a mystery.

 

[JasonLion]

CYA drops only very slowly during the pool season, unless you replace a lot of water. It does go down, but not quickly enough to be useful. Over the winter, CYA can go down much more quickly, but that is very unpredictable, sometimes it happens usually it doesn't.