I got the foam on line a few years ago. They cut it to what ever size I wanted. It was much cheaper than in the store. I got about 12 pieces to do cushions for my outdoor wicker. If you only need one piece, the coupon from Joann's is good. Just google foam cushions, and you get a whole bunch of them..all thicknesses, etc. Good luck with your project!

Hi Nick-- We have a similar situation with our pool, if I understand your question correctly. If your plumbing is set up like ours, the spa and pool run independently through the pump and heater. When the spa is on, the pump is only pulling water from the spa skimmer and floor drains then returning that heated water to the spa jets. Our gas heater has separate settings for either spa or pool mode, so we can run different temperatures on each. When the spa is off and the pool is on, the pump is only pulling water from the pool skimmer and drain and returning to the pool via in-floor cleaning heads. There is no cold water from the pool coming into the spa (unless we change the valves to purposefully do that). Your question is finding a cover to put on the spa that will help maintain the temperature while the spa is not in use, from one night to the next. We live in Kansas City where the nights have been getting down to freezing, so our spa water temperature has been dropping about 20 degrees from one night to the next. We haven't started covering it yet, but we also have a blue "bubble wrap" pool cover (from a previous pool) that we are planning to try to see if it helps any. Our PB did recommend a floating foam cover made from material similar to foam pool floats but thinner. I think he said it is about 1/2" thick, so it can be rolled up when taken off. The price range was a couple hundred dollars he thought (our spa is semi-circular about 10' x 15'). He didn't mention the name of the vendor he would order it from, but it does exist. This may be what you already found online, but it was the only solution our PB had for us. Let me know if you find something better. Here is a link that might be useful:

I don't know how to do this by mail order because all chunks of foam are not equal. Some condense easily when you sit on them and some are more firm. So for that reason I'd go in person to a store like Joann's and I'd ask if I could actually feel, and maybe sit on the foam to check it out so I'd know how thick I wanted it. My hunch is if you go with 2" you are going to need side welting, but again it depends on the foam. Maybe if you take a chair bottom with you they will cut it to fit for you too. Or, you can use an electric knife if they won't.

I bouight a bed a couple yrs ago from a company that manufactures their own mattresses including custom work - that sort of place could probably do it for you - they have all kinds of interesting equipment.