Regardless of your pool heat source, you should use a solar blanket to keep heat in your pool, and this video shows you why! When pools are warm and night (or day) temperatures drop, heat escapes at a very fast rate from swimming pools. Lost heat makes doesn’t mean solar pool heaters won’t work without a cover — it just means it will take longer to heat back up. Not covering a gas or electric covered pool is like leaving the doors open with the air conditioning running. If you have the money to do that… good for you! Go for it! Otherwise, cover your pool for the best results and lowest heating cost.
Note: This is a Southwest Florida pool in February!