Swimming pool cooler - interim report

I posted before on this subject and got some good ideas. The goal is to keep the pool from heating up so much (to 92 or so) during July and August so that it becomes unpleasant to swim. My pool plumbing doesn't lend itself to using a fountain, so I've tried to think of ways to block the sunlight from reaching the water, since it appears to be sunlight, and not ambient temperature, that's responsible for the excess temperature.
So as a test, I built one 10 x 5 foot frame of 3/4" PVC pipe (the 200 psi thin-walled stuff), covered it with "bird block" netting, then a layer of aluminum foil strips with a 1" gap between them, and another layer of bird block. I used metal tape to secure the various layers to the frame.
Originally I wanted the foil strips to stay just above the water so that evaporation could still take place, but the PVC frame isn't stiff enough, so I ended up with the foil layer just lying on the surface of the water. It appears not to want to blow away, so far, but it is a bitch to put on and take off in the breeze - it's just a big sail.
Since this panel only covers 50 sq ft out of the total 575 sq ft of the pool surface, it's hard to tell how much effect it has. But it's clear that if you stand on the deck where the panel is reflecting the sunlight up at you, you feel a blast of heat from it, considerably more than if the sunlight was just reflected off the water. So my guess is that the foil is a pretty good reflector, and could potentially keep a good bit of heat from entering the pool. It's far less clear what percentage of the pool surface you would have to cover to materially affect the temperature. Basically, I need about 6 degrees max. I was hoping 50% coverage might do it.
This panel is too big and too flimsy. But if it works with the foil resting on the surface (no evaporation), then I need to go back and look at the 4 x 8 insulation foam panels with foil backing. They would require no construction, be cheaper, and much easier to put on and take off when the wind is blowing, and easier to store. I just don't know if they would hold together in water, or if something bad might leach into the water from them. Any thoughts on that?
Whatever I use, it would need to be on the pool during periods of direct sunlight, but removed at other times. That's during the high summer. But I think in spring and autumn, I could reverse that, and use the panels as a heat blanket at night, and remove them on sunny days.
I'm sure some of the solar energy still transfers through the foil to the water, but I was really surprised at the heat wave that reflects back up at you from it. So this was an encouraging experiment.
I have pictures of the frame, before and after the foil layer was put on, but I don't have a website, and Cox won't let me post a picture to this newsgroup. Is there a "binaries" newsgroup that you guys use to post pictures from here? Or I could email them to someone.
I'm beginning to think something like this might actually work. It would involve some trouble to put on and take off, but really only a couple minutes. So I'm going to keep playing with it.
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Try a product like this. It should be as easy to use as a solar blanket, but it has a foil layer to block the suns rays.
http://www.ayr-foil.com/ayr-foil-reflective-insulation-technical-datasheet.aspx good luck..stay cool, Doug

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"BiffNightly" wrote

=Hmm--They now make solar blankets with reflective coating underneath to increase heat retention in the water. Why couldn't one simply put that cover on upside down (with the reflective coating up to deflect sun)? ==>

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Gini says...
> Hmm--They now make solar blankets with reflective > coating underneath to increase heat retention in the > water. Why couldn't one simply put that cover on upside > down (with the reflective coating up to deflect sun)?
I haven't seen any official pool blanket with foil on the top, or bottom, and that's the first thing I looked for. I found one with some other kind of "reflective" coating, but it wasn't foil. If you know of one with foil, a link would be helpful.
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"Peabody" wrote

=This is the one I had in mind.
http://tinyurl.com/2zoeg4
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Gini says...

Yes, I'm just not sure that's anywhere near as reflective as a real foil layer. But I'll try to get more info on it. Thanks.
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BiffNightly says...
> Try a product like this. It should be as easy to use as > a solar blanket, but it has a foil layer to block the > suns rays.
> http://www.ayr-foil.com/ayr-foil-reflective-insulation-t echnical-datasheet.a spx
> good luck..stay cool,
I found something like that at a local store, but it turned out to be rather stiff, and wouldn't lay flat on the water. And, of course, it therefore tended to blow away.
I haven't been able to find anyone who has actually used foil-backed bubble wrap, or foil backed foam boards, for this purpose. I've found people who've used fountains (which I may end up usig in the end), but not the other things. I would have thought this would have been a major product in Phoenix, but apparently not.
It seems strange to me that the makers of official solar blanket pool covers have not introduced the opposite product - the one with foil to keep the water cooler. Maybe it's because the pool stores wouldn't sell it since it would cut down dramatically on chemical purchases. Or, maybe it's because it just doesn't work. Don't know.
Well, I may break new ground here. :-)
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