I think they're fine as long as you don't use the pool (!) or the wind doesn't blow; once the surface layer is disturbed the liquid has to be replenished.

Steve

Never tried the solar thingies, but I love your blog!

Heat saver is the common product and after having my arm twisted at a trade show that this was the best thing since, oh anything, I got a free jug. Used it as advised and was literally told that I would not see steam coming off the pool. Well, that was a joke. The pool smelled like red wine for a week and there was no change in surface tension on the water as advertised. Try Solar Sun Rings as a cheaper alternative to a bulky cover.

Thanks for the heads up about the liquid solar cover, it does sound too good to be true. I did try the solar sun rings, lots of them, but I just didn't get a big enough bump in temperature to make it worth the effort to keep them inflated and clean. Imagine how soon I lost my patience because every time we used the pool I had to stand on the pool deck blowing up the outside flotation rings on 20 disks before I could throw them back on the surface usually at midnight when I remembered that I had forgotten to replace them. I grew weary of that routine. They went in the bin at the end of the season and that was a lot of money to send off to the landfill.
I might try the two part solar stick I saw mentioned on another post, that looks like something I can handle by myself.

womanontheverge: I was intrigued by repair guy's suggestion for Solar Sun Rings and checked them out last night online. I thought they seemed a whole lot easier than using a big bulky solar blanket and might be easier to store behind my equipment wall (I would need about 16). Then I read your comments above regarding having to blow them up before each use. Do they not hold air for long? That would be a huge drawback.

They work best just slightly under inflated. The idea is to keep them a bit wet so they stay. They claim 13k btu each and in hot areas they work great. They do not need inflated each use. Hang them up when not in use and toss them back.

Thanks repair guy. Helpful information!

Saw this on ebay!

Here is a link that might be useful: do it yourself disks

The instructions also suggest under-inflated for the outside flotation circle, but most of the rings developed leaks on outside circle and wouldn't stay inflated at all. We get really hot here (SLC) during the summer, but evaporation or cool nights or something takes the heat out of my pool every night and the rings didn't stop that from happening. Which leads me to another question I'll go naively post right now.