Bleach & Vinyl Liner

[chem geek]

It's not a problem for your sand filter. There is the possibility of some wear with a cartridge filter which is why I don't pour it in the skimmer in my own pool, but I'm being conservative. Unlike pouring acid in a skimmer, which is an absolute no-no, I don't think there's ever been a report of problems pouring chlorine through the skimmer -- again, I'm just being conservative by pouring it over a return flow at the deep end.

Richard

[elsie]

If running high chlorine consistently causes liners to fade, then why wouldn't everyone, at least here in the south where the water doesn't freeze, who shocks and covers their pool in the fall open in the Spring to a faded liner? I close with 15 ppm CL and open 8 months later to a ppm of 8, which means the liner was subjected to a high chlorine level of 15 ppm over an extended period of time (before it eventually dropped down to 8 ppm at some point before the Spring). This makes you wonder about high CL fading liners in the first instance, doesn't it? If not during those long winter months, then why in the summer when the pool's open, and when high chlorine doesn't consistently stay high unless treating for algae, and even then it's a limited time -- certainly not month after month? UNLESS, fading results from a myraid of other reasons such as the interaction of high CL and sun and/or other chemistry values.

When I switched to the BBB method some years ago (2003, I believe, a year after I bought my property and inherited my pool), my liner began fading quickly, not just in the deep end where I pour the bleach in front of the jet, but the shallow end as well, which is far from that deep end jet so it's not localized fading. And, although it sounds like it, I am not blaming the BBB method -- the fading just coincided with my 2nd year of ownership. The sides are not faded, but I have almost no color left anywhere on the bottom (and the seams are very visible with a thin line of black). Yes, I do tend to run my CL a little on the high side because I have continual debris from the trees entering the water (I check pH religously and ordinarily add a cup each week as the pH tends to rise with this method for me), but still, this brings us back to the question above: not using my pool as an example, "if consistently high chlorine fades liners, why not when it's covered and the CL level stays consistently high for a number of months?" Surely we would hear reports of this from pool owners all over if they were opening to faded liners, and we don't hear such reports. The fading of my liner, hence, remains a mystery.

Fortunately, it's never bothered me. With the color intact on the sides it still shimmers aquamarine. My liner is a good 10 years old I figure, and still not showing signs requiring replacement. I'm crossing my fingers that the faded liner does not diminish integrity of the liner, and that I can squeeze another season out of it in 2009.

[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?