My experience with liquid solar blanket
I’ve seen ‘tropical fish’ and ‘solar pill’ liquid blankets. It is just wax in isopropyl alcohol. The alcohol is water miscible and will evaporate. The wax forms a layer on the water to reduce evaporation. Evaporation causes temperature loss in pools as it takes a tremendous amount of energy to go through the phase change.
Worst it could be was a terrible mistake, so decided to try it. I bought several liters of “Liquid Heat Solar Blanket” on Amazon of all places. It's made by the same company that does the ‘solar fish’ and is designed to be used in a dosing system.
The last 4 weeks I’ve been spreading 1-2oz per day over my 800 sq ft (estimate) pool after we are out of the pool for the day. Instructions call for 1oz/day/400sq ft.
Results: It has worked pretty much as advertised! Pool has needed makeup water twice in the last 4 weeks, vs. every couple days previously. Pool temp has hovered 78-80F, despite shortening days, winds, and low humidity. We still use the pool 'most every day. There is a slight oily sheen to the pool if you can catch the right angle – have to look for it, not objectionable. No noticeable waxy residue anywhere.
I intrigued at the possibility of using it all summer to reduce water loss and rising CH. The pool goes through (best guess) 150gal/day or more in summer. Managing CH has been a hassle, 200ppm incoming water, pool climbs above 400ppm very quick. Running around 475 right now.
So: Your Mileage May Vary, but (so far) I like this stuff. I will attempt to whip up my own with high-grade paraffin and isopropyl alcohol
Enjoy the awesome Autumn folks!!