From a local, repsected pool dealers webpage...

[chriscard25]

Q: How much is too much stabilizer?

A: A common myth in the pool industry claims that too much Stabilizer (Cyanuric Acid, CYA) in pool water "locks-up" the free available chlorine residual. Chemically, this is not accurate. The free available chlorine residual kills microorganisms with CYA levels up to 500 ppm. Minimum CYA level is 30 - 40 ppm, acceptable is 30 - 200 ppm for residential pools.

 

[waste]

Thanks!

Sure, they say that up to 200 is fine, but they're also the ones who sell the chems to 'fix' the problems 200 ppm cya can cause

 

[woodyp]

At least that explains why those folks walk out of the pool store with a case of powdered shock under each arm.

 

[Hilton]

Can I ask what your source is for this? British Columbia health authorities recently started testing for CYA as part of their inspections due to the problem of "chlorine lock". They close your pool if they find CYA over 80. Not a problem for me, since the only time I see CYA that high in anything is hot tubs using trichlor pucks, and usually by the time I reach 80 CYA it's due for a drain anyway (due to high TDS).

 

[Richard320]

:google:

I just did. At least three places have the frst line verbatim. So the source is likely one of their vendors..... Bioguard is my hunch.

 

[JasonLion]

If you can handle some semi-advanced chemistry, you should take a look at this post, which explores the chlorine/CYA relationship. The sanitizing ability of chlorine can be maintained as the CYA level rises as long as you proportionately increase the chlorine level. Of course, at high CYA levels various side effects make that impractical.