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
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
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
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
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.