Bleach & Vinyl Liner

[aylad]

Speaking as one of the pool owners in the South who does also consistently keep higher chlorine levels, I'd just like to throw in that I'm on my 7th season with my liner, pool open year-round, BBB since the beginning, and the only fading I see in my pool is above the waterline. If you keep the chlorine consistent with the CYA requirements, I think the sun is more likely the culprit.

Janet

[elsie]

Yet with higher CL values and presumably a lot of sun (as I recall you keep your CYA higher in order to hang onto CL because your pool gets direct sun for a long time each day), the floor of your liner has *not* faded. On the other hand, my pool gets a meager five hours of sun each day. So the fading question must point to something else other than CL + sun logic tells me.

One of these days my curiosity is going to drive me mad!

[chem geek]

The higher CYA level slows down the chlorine loss from sunlight in two ways, but one of those ways is in shielding lower depths from the UV rays of the sun (the CYA directly absorbs UV rays). This is a non-linear effect such that higher CYA levels significantly reduce the amount of UV that reaches lower depths. So it is quite possible that Janet's higher CYA level protects her vinyl pool bottom from fading while your lower level doesn't, even with less time in the sun.

I also seem to recall that Janet's pool is deep with a maximum depth of 8 feet. Even at the same CYA level, that would also make a difference.

This would imply that a higher CYA level would be a way to have vinyl liners fade more slowly, at least at lower depths, but that requires diligence since you have to maintain a higher FC level and it's harder to fight an algae bloom at higher CYA levels.

This is all nice theory, but we don't have enough cases to know if this is truly what is going on.

Richard

[ChuckD]

And just to throw another variable into the mix, I think it could be safely stated that all vinyl liners are not the same. Or at least the way they're colored.

I'm another who's shocked many times over the past three years I've owned my pool. The liner's 8 years old (I have the receipt) and the colors are still quite vibrant. Like Richard, I add 12% at the return in the deep end and always allow it to circulate at least an hour after. I'm thinking there are dyes used to color the vinyl that may be more susceptible to chlorine than others, not unlike clothing in the wash.

C.

[elsie]

Interesting variable to be sure -- maybe that's the culprit behind my fading. It's the only thing that makes sense, in fact. I wonder if the dye--or the life of the dye--has anything whatsoever to do with mil thickness (I have no idea what mine is). Speaking of which, any idea if, when one goes to replace the liner, it pays to get the thickest mil on the market?