Solar Rings
I bought about 12 of the Solar Rings last season and that didn't cover the entire pool but about 75%. I live in Central NJ, and while it does get hot here (my pic is the last recent entry on the submit your photo for the slide show thread), our pool location has a lot of very tall established trees and we are up the "mountain" a bit so our overall temp can be 3-5 degrees different than just being in town. So we bought the rings. My biggest issue with the rings is that you have to inflate them! I could never get mine to look like the way they look in the photos. If you put too much air they curl on the sides, or fall into the water when underinflated. The directions say not to overinflate, it is really hard to know. They come all folded up, so getting the air in is difficult.
My pool's ambient temp tends to be around 72-76 (I know that is kind of cold), the Solar Rings would bring the temp up to a more consistent 78-82. I hardly ever got over 86 unless it is really, really hot for an extended period of time and there is a lot of sun. My pool does get shade depending on the angle of the Sun.
I am thinking of trying to return them to the maker as defective, because some of the rings get water in the air channels through the blow-up valve, so they actually have water in the part that is supposed to be blown up. I really wanted to put a solar blanket on a spool, but my husband didn't like the look of it and thought that the wind-up spool things was expensive. In comparison, the Solar Rings were just as expensive and more of a pain to blow up. I actually think that the idea is a good one, the application is flawed. IF the solar rings were a pop-up type of mechanism (like a pop-up pup tent) or a Hula-hoop type thing, they might work better. I tell you when I had to pump-up 12 rings by hand, and (when my hand got super sore) blow-up the rest, I was not a happy camper!
If you have any other questions, I would be happy to answer them. I am sure I am sending them back.