Blue Rectangle Solar Pool Cover Cuttable Pool Heater Covers Heavy Duty Insulating Bubble Blanket Dustproof UV-Resistant for Swimming Pools

It's two things .. Open each side panel and loosly stuff the entire volume with unfaced attic insulation. Don't forget to push some up under the lip, and shove some into the corners. I would recommend wearing gloves and a cheepo face mask, doing one panel at a time, and reinstalling before the next panel. Keep insulation 2-3" from the motor/pump. Something like this: https://www.homedepot.com/p/Owens-Corning-R-13-Unfaced-Fiberglass-Insulation-Batt-15-in-x-93-in-1-Bag-E51/100320320 2. Get a sheet of that solar pool bubble cover on Amazon. Cut it as close as possible such that it floats, bubble side down, on the surface of the water. Something like this: https://a.co/d/0itO9Y2q