With energy prices increasing, it makes sense to decrease the amount of time your heater is on. Your spa loses the majority of its' heat through the solid cover. You have probably seen fresh snow disappear off the cover while the deck is still covered with snow. Even the best covers are guilty of this. However, using a thermal cover under your hard cover will drastically increase the insulation value.
How do they work?
You cut the plastic blanket to the same size and shape as the water surface of your hot tub. This blanket is filled with thousands of tiny air sacks that allow it to float on the water surface, underneath your regular hard cover. By using two covers in conjunction with each other, you will maximize your spa's heat retention. The hard cover keeps the cold air out and the thermal blanket keeps the heat in the water. It works on the same concept as a double pane window.
Floating covers prolong the life of your hard cover!
Using a floating cover will decrease the amount of steam that is eating at your hard cover. Steam at 100° Fahrenheit that contains spa chemicals, will eventually erode away at cover seams and linings. Old worn out covers will eventually start to absorb water and begin to get heavier, putting more pressure on the cover seams. An economical hot tub thermal blanket will help prevent this and often triple the lifetime of your $400 hard cover!