Solar Blanket vs Plastic???

[shadowman]

I think most of us agree that the main advantage of a solar blanket is to reduce evaporation at night and its corresponding heat loss. I can certainly testify that there is little heat gain during the day, at least at my location. My question is, why can't we just float a heavy piece of plastic sheeting on the water? Or would it just sink? Spending money on all the cute little diamond shaped bubbles that break down in the UV rays seems foolish if there is an alternative way to stop evaporation.

Set me straight all you experienced experimenters! :D

[JohnT]

I believe it would sink.

[cleancloths]

Most plastic is lower density than water and won't sink --BUT if you get a lot of water on top of it then it will submerge. The bubble type plastic basically entrains air in the bubble which makes the plastic float better.

[CarlD]

I have found that solar covers DO heat the water. I think it's a myth that they don't. I've had blue, opaque (black underneath, blue on top) and clear. I thin the blue ones don't heat too well but the opaque and clear ones do. The opaque heat by conduction--the water right under can get hot where it's next to the black (but why the blue is on top and the black down is a mystery). Clear and blue heat by letting the sunlight through--clear lets the most through.

I have a blue one now and it's far inferior at heating to its clear (but far more expensive) predecessor.

Of course I rely on solar panels primarily, and the cover is to hold the heat in.

The bubbles not only ensure the cover floats, they provide dead air space, which is the best insulator short of a vacuum.

[shadowman]

Yes, I suppose it would sink. My blue one is currently disintigrating after 3 years and I am just grasping at straws to save a few bucks on its replacement. :rolleyes:

Thanks for your input.

[CarlD]

Yes, I suppose it would sink. My blue one is currently disintigrating after 3 years and I am just grasping at straws to save a few bucks on its replacement. :rolleyes:

Thanks for your input.

I've had cheap ones and expensive ones. After 3 years even the most expensive with the 10 year warranty falls apart--then I found the warranty only applied to seams de-laminating....which almost never happens. The bubbles start popping by the thousand but that's not covered. And it starts mid-way to the end of the 3rd year. So my newest cover isn't as good, but since in 3 years it will be trash anyway, I spent half as much.

[Tredge]

I think its worth a try. I'd love to see how a perfectly clear sheet of plastic over the pool performs.

Hard to believe this hasnt been tried.

[Tredge]

Found this good Article on the subject.
http://www.rlmartin.com/rspec/factsheets/covers.htm