It's best to use a cover designed specifically for swimming pools. You can use a sheet of plastic, but it will be very inconvenient and it will probably only last 1 to 2 seasons maximum.

It will be very difficult to handle and store, it tears easily, and sunlight will deteriorate it rapidly. But a large sheet of plastic that you get from the lumber store is probably not your best choice. Plastic meets the requirement of being a vapor barrier. Technically, all you really need for a pool cover is a large sheet of plastic. You can also shut off exhaust fans when an indoor pool is covered, which saves even more energy. Pool covers on indoor pools not only can reduce evaporation but also the need to ventilate indoor air and replace it with unconditioned outdoor air. Covering a pool when it is not in use is the single most effective means of reducing pool heating costs. Pool covers minimize evaporation from both outdoor and indoor pools. The ventilated air also must be conditioned, which adds to the energy costs. They even require room ventilation to control indoor humidity caused by the large amount of evaporation. Indoor pools aren't subjected to the environment, but they still can lose a lot of energy from evaporation. You also don-t want the windbreak to shade the pool from the sun, which helps heat it. The windbreak needs to be high enough and close enough to the pool that it doesn't create turbulence over the pool, which will increase evaporation. In windy areas, you can add a windbreak-trees, shrubs, or a fence-to reduce evaporation. The higher the pool temperature and wind speed and the lower the humidity, the greater the evaporation rate. The evaporation rate from an outdoor pool varies depending on the pool's temperature, air temperature and humidity, and the wind speed at the pool surface. It only takes 1 Btu (British thermal unit) to raise 1 pound of water 1 degree, but each pound of 80✯ water that evaporates takes a whopping 1,048 Btu of heat out of the pool. Evaporating water requires tremendous amounts of energy. Swimming pools lose energy in a variety of ways, but evaporation is by far the largest source of energy loss. Use of a pool cover also can help reduce the size of a solar pool heating system, which can save money. Estimating Swimming Pool Gas Heating Costs and Savings.Estimating Heat Pump Swimming Pool Heater Costs and Savings.On the following pages, see the tables showing the costs of heating pools with and without pool covers in different U.S. You can significantly reduce swimming pool heating costs by using a pool cover.

Automatic pool cover wheels