Will Liquid Pool Shock Bleach my Liner?

[sparker]

Good morning all, my pool pump went out a couple weeks ago before i had a chance to put chemicals in and circulate to close. i thought I would wait to buy a new one next season.

The guy at the pool supply store said he just uses 2-3 gallons of Vertex CSS-12 liquid pool shock and algecide then just lets it disperse in the pool without circulation from a pump.

Is there a chance that this much liquid pool shock would bleach my liner? The pool is 10 years old and just had the liner replace last year.

My wife seems to think this will happen.....i don't want to be told next year when i take the cover off "I told you so".

Thanks Scott

[PoolDoc]

Yes, there's a chance it will.

It depends on

• the % concentration of the bleach, which may be more or less than labeled, for several reasons
• the volume of your pool
• and, most of all, on the composition of the liner print

Unfortunately, liner patters & colors vary a lot in their resistance to chlorine levels, though the underlying PVC material is pretty consistently resistant. And, even more unfortunately, there is no way I have found in 30 years of pool work to distinguish liners prone to fading from those that are resistant.

Well, you can tell after they've faded. But in advance? Nope. Never found a way to do that.

So . . . no matter what you do, the liner may fade.

And, without knowing your relationship to your wife, I can't be sure about any advice. But the prudent thing might be to say, "I'll do it however you like, honey. How do YOU want me to clear it up?"

Just don't drain it: that WILL destroy the liner, or at the very least, require professional assistance to reinstall it. Liners are held in place with shop vacs, while warm and stretchy, and then by water afterwards. But they loose elasticity after installations, so when you drain them, and they shrink, they tend to tear when stretched back into place!

But, as far as the facts of chemistry go -- and those seem often to be irrelevant in discussions between married couples about their pools -- bleach adds the same kind of chlorine as any other sort of chlorine. But it does not contain stabilizer. If your pool is un-stabilized -- and green slime often eats stabilizer. Literally! -- then dumping a lot of chlorine in all at once CAN bleach most liners. On the other hand, if it still does have stabilizer, then liner bleaching is much less likely.

There's another issue.

The way slime eats stabilizer is interesting, and complex. (This Brazilian paper [ http://repositorio.ul.pt/bitstream/1...c080506_tm.pdf ] (mostly in English) covers the details nicely, you want the gory details.) But the somewhat rude version is that various bacteria 'eat' the cyanuric acid, and then 'poop' out other chemicals, lower on the pathway. These chemicals include urea and/or ammonia, both of which react in nasty ways with chlorine. However, after the first batch of organisms die off, a second batch comes along to 'eat' the 'poop' of the first batch.

If you do not interrupt the process, it will continue till nitrogen gas or nitrates are formed. These are NOT a huge (or even any, in the case of N2) pool problem.

Moral of this story? If your stabilizer has disappeared, it's probably better to let the 'eating' and 'pooping' process continue till spring, so you don't have to fight the ammonia and chlorine. But if your stabilizer is still present, you can do as you like.

Regardless of everything else, monitor and control your pH levels.Low pH (< 7.0) damages ALL liners. And, high pH (>7.8) can allow some really nasty things to happen, biologically.

Good luck!