Using a good pool cover is the most effective thing you can do to save pool heating costs and reduce greenhouse gas emissions. Not to do so would be like running your house air conditioner during August with the doors and windows open. The system will still work, but the operating cost will be as much as three times" higher.
Automatic pool covers save up to 70% of heat loss from a pool and 90% of its water evaporation. This will save a pool owner in the cost of adding water and chemicals. Additionally, a homeowner can save up to 50% on the electricity costs to run a pool. The pool filter cycle times can be reduced up to 50% which will also reduce the electricity costs. Beyond the savings afforded to pool owner, you can contribute to our environment by reducing the pools carbon footprint.
To see sample costs savings samples goto the U.S. Department of Energy's savings comparison for gas heated pools at their Energy Savers website.