Passive Heat Using Homemade Solar Disks

[alisonquilts]

So that I do not run afoul of the Forum's rules I will say upfront that I have no connection to the pool industry, and that this post is in no way aimed at making money for me or anyone else!

When we first got our pool three years ago I was determined to heat it without using additional energy (already feeling a bit guilty about the general environmental unfriendliness of pools...) so I looked around for alternatives, and was not happy with what I found. Our best bet was a solar blanket, but this wasn't a great fit for us because we have a very oddly shaped pool, nowhere convenient to site a reel, and because our daughter was quite young at the time (I was afraid she would get trapped underneath - *shudder*).

What I did stumble across was a variant on the inflatable solar rings in vogue about four years ago (the kind that rip, blow away and generally are ineffective, from what I have heard). The version I have are homemade rings made of the tubing you use if you are installing drip irrigation, and circles cut from regular pool solar blanket material attached to the tubing with the plugs used in drip irrigation systems ("goof plugs"). The rings can be any size (mine are about 4' across) and for optimum heating/evaporation reduction should cover 75% of the pool surface (mine cover about 60%). The tubing gives the rings enough weight that they don't blow around too much (although the return jets do tend to stack them up after a few hours), and you can swim around them and under them without worrying about being trapped (they don't weigh very much). They stack neatly on the pool deck, and are not unattractive while floating in the pool - picture big blue lily pads. And they actually do serve as refuges for some of the critters that fall into our pool...including frogs!

I would like to make extravagant claims for their effectiveness, but since I only have one pool I have not been able to do any controlled experiments regarding heat absorption/retention and evaporation. My husband and I both feel pretty sure that they help significantly, and are worth the effort. When the days start to shorten, and night temperatures start to drop sharply in late September our disks are no longer particularly effective - they still slow the pool's heat loss, but not enough to keep us swimming. (Our pool is half-shaded, and the angle of the sun in autumn means that there is very little direct sunlight hitting the pool after mid-September.)

The initial cost (three years ago) was about $200 for 36 disks, and all 36 are still in good shape. I plan to make some more this fall to get up to the magical 75% coverage. Theoretically, when the initial piece of solar cover wears out it can be removed from the ring and new material added (I have not needed to do this yet), which makes replacing worn out rings relatively inexpensive.

I have tried very hard to find the person who originally came up with the plans (about 6 years ago, I think) so that I can credit them, but I have had no luck. They titled them "Floating Solar Disks".

Alison