We just did ours, once it stopped raining it wamed up pretty quickly. It really depends on all sorts of variables, including how much sun you get, how dark the finish is, and the overall depth.
We picked up about 10 degrees in a week once it got sunny.
@ET: Oh wow, so it could take 3 weeks for it to get warm enough to swim. Sighhh. Thanks for the info
@ET. Who did yours?
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