Liner badly faded where sun hits it most

[singerteacher]

Our liner has been through 7 seasons, and 6 of them have been BBB. We just closed the pool, and although there has always been some liner fading each year below the water line, it's much worse than usual this year. It starts at the water line and seems to go down the side, but doesn't affect the bottom much. It's much worse on the "sunny side" of the pool, but the "shady" side is also affected. I'm trying to figure out the cause, so we don't make it worse. Two things come to mind:

1) We have never covered the pool in the winter. So, the sun beats on it all year long -- and actually, we do get lots of winter sun in Wisconsin. Possibly making matters worse, it fills with snow and the sun bounces off the snow. Would it help to cover it? There is a black vinyl cover, but I dread getting the water and snow off of it all winter long. We've had no problem opening the pool in the spring, so if there's not a compelling reason to cover it, I'd rather not. We've thought about purchasing a leaf net cover, but I'm not sure that would help the fading issue.

2) I had a heckuva time getting my CYA to the proper level this year. I kept adding it, and even though I was adding the proper amount for my pool size, I kept having to go buy more; then I'd test, and again it would need more. And once I got the CYA to the right level, a week later, it was too low again! (It's always been this way, but was really bad this summer.) As a consequence, we did have to use more bleach than usual. (No, I don't backwash excessively.) Could this have been the problem?

In all other aspects, the liner seems to be fine. It just doesn't look too good, especially when it's drained!

 

[Patrick_B]

Well a leaf net might offer a little shading, but it's hard to say it would be enough. Can't blame you on not wanting to deal with the snow/water all season long. Not fun in a WI winter I'm sure. It does sound like the sun is causing your trouble, unless you are getting really high FC with very low Cya, but I'm guessing you have a pretty good handle on it using the TFPC method for six years.

The first question I would as on a Cya issue like that is do you have a leak in the pool?

 

[singerteacher]

Re: CYA loss. I did the evaporation test (bucket of pool water on the steps), and both the bucket water level and the pool water level seemed to drop the same amount. Our pool does get pretty heavy use (kids in it almost daily), so the splash factor is part of the equation, but it doesn't really explain how we can lose so much CYA. My personal theory is that something that goes into the pool reacts with and possibly changes the CYA. We always have 0 CYA in the spring - every single year. And it's also hard to maintain CYA every year. (The worst this year, though.) I've wondered whether it's GM pollen from nearby corn fields, certain kinds of leaves, or our city water when I refill, which is not the best (nitrates, nitrites, arsenic). I'm not the only person experiencing this phenomenon -- it's a job for a chemist!

 

[singerteacher]

Tangent: In this very interesting article about going CYA-free, the author has a system that keeps his chlorine at a standard level constantly. I'm wondering whether a SWG does this, too, so one could go CYA-free? Adding CYA is a constant battle for me.
http://truetex.com/poolcontrol.htm

 

[singerteacher]

CYA and melamine

Um ... could my Magic Eraser, which I use to clean the steps and coping, be the problem?

Apparently, Magic Erasers are melamine foam. They work really well to eliminate stains, but dissolve as you use them. I probably dissolve 3/4 of a Magic Eraser into my pool whenever I clean with it. Apparently, melamine binds with cyanuric acid to create melamine cyanurate -- this is the chemical reaction that allows us to determine the CYA level in the pool test kit.

Could this actually be what's happening? Is one Magic Eraser enough to drop my CYA level?

I also read that melamine is used in concrete. Too much melamine is very bad for kidneys (as is CYA, according to the Wikipedia melamine entry), causing kidney stones and possibly renal failure. Another good reason to keep CYA at 30ppm. And no more Magic Erasers for me!

 

[Patrick_B]

I will read the link but want to answer now. Cya in a SWG is very important. A SW cell usually needs all the help it can get. Very strange that you lose so much, and are you saying the phenomenon is something local to you, that others close by see the same thing?

 

[singerteacher]

Apparently, melamine is added to fertilizers. So we may be getting melamine in the pool from fertilizer dust, as well. We get a cloudy pool every time there's a big rainstorm.

 

[singerteacher]

Re: CYA loss

I haven't checked with my neighbors about CYA loss. I do think that dissolving a Magic Eraser in my pool a couple times a summer could cause CYA loss, but I'm not sure. Also, melamine in the fertilizer dust and possible melamine in our cement ... all of these things together might be eating up our CYA. That is my guess, but I'm not a chemist!

 

[singerteacher]

Back to the sunlight fading problem:

I wonder if there are any pool covers that allow water to drain through? I'm picturing a pool cover with a drain hole in the center. This would keep the sunlight and leaves out of the pool, but allow the rainwater and melting snow to pass through. That might be a good solution for us. Does it exist?

 

[linen]

Tangent: In this very interesting article about going CYA-free, the author has a system that keeps his chlorine at a standard level constantly.

Although some of the authors comments have some validity, particularly when referring to "over-stabilized pools" such as those that happen when trichlor pucks are used as the only chlorine source, it does not apply generally to properly stabilized pools (30-50 ppm cya for a non swg pool). He has another motivation for lower cya since orp controllers tend to have problems as cya levels go up. Since he is apparently able to have real time feedback and adjust his dosing (but not without a lot of work), he may be able keep his FC level fairly close to level. However, his pool is likely too high in "disinfecting chlorine" levels and be hard on suits and skin in his application (I do not see anywhere in the article where he lists what FC level he is maintaining) since he would ideally want to keep his FC at <1 ppm or lower. Additionally, it may be difficult to keep this low level of FC throughout his whole pool, so having good circulation (lots of turnover=lots of electricity) would be important. Also, his approach will end up using more chlorine since the sun will consume a lot of what he puts in.

In the end, it sounds like it was a fun project for him, but it is not practical or necessary.

 

[linen]

However, his pool is likely too high in "disinfecting chlorine" levels and be hard on suits and skin in his application (I do not see anywhere in the article where he lists what FC level he is maintaining) since he would ideally want to keep his FC at <1 ppm or lower.

I missed it in my first read and just found that he is trying to maintain 0.5-1.0 ppm FC which should work, but is still higher than needed when cya is 0, significantly higher in "disinfecting chlorine" than our regular maintenance FC levels recommend for cya of 30-50 ppm, and therefore "harder" on suits and skin. To give perspective 1.0 ppm FC at 0 ppm cya is equivalent to ~25 ppm FC at 50 ppm cya levels.

 

[Leebo]

Re: CYA loss. I did the evaporation test (bucket of pool water on the steps), and both the bucket water level and the pool water level seemed to drop the same amount. Our pool does get pretty heavy use (kids in it almost daily), so the splash factor is part of the equation, but it doesn't really explain how we can lose so much CYA.

How much water a week do you replace???
How much does your CYA level drop each week???

 

[linen]

Re: CYA loss

I do think that dissolving a Magic Eraser in my pool a couple times a summer could cause CYA loss, but I'm not sure.

From this thread:

I think however that 1 lb of CYA requires about 1 lb of melamine. I think the molecular weights are similar. So each 12 ppm of CYA in 10,000 gallons needs 1 lb of melamine and produces 2 lbs of precipitate.

From this info, it would take a lot of melamine to reduce cya significantly in your pool.

 

[Bama Rambler]

Re: CYA loss

From this info, it would take a lot of melamine to reduce cya significantly in your pool.

Especially since each Magic Eraser only weighs .07 Oz (7/100ths of an oz). A couple of them a year would make absolutely zero difference. All the melamine gotten from fertilizer, concrete and Magic Erasers would make no difference.