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Keep the cover on.Don't expose an empty hot tub to a hot sun if at all possible.
In the last 3 hours, with the lid closed the tub has gone up 3 degrees.  I'm guessing I should have just left the lid closed all day.  Its down to 92 outside now and 90 in the tub.  Not to bad...Oh, and we didn't have power from about 12-4 today so there was no heat from running the circ pump or anything.
I cleaned the cover for the first time. Â Note to others: Â Clean off bird poop immediately. Â It takes the color right off the cover.