If you love swimming and wish to extend your swimming season from earlier in the Spring until later in the Fall, a solar swimming pool cover could be an economical means to do this. Presently a solar pool cover will not keep the water warm as a pool heater will, but it will surely help keep the heat in the pool.
Solar swimming pool covers are basically giant sheets of bubble wrap that you set on the pool to help heat the water, faster, and keep it warm. You place the cover on at night to keep the warmth in, and take it away in the morning so the sun can warm the water a while.
Doing this every night for weeks or days (depending upon where you live) will warm your water much quicker than if none is used. This will begin your swimming season a little earlier in the Spring and if you repeat it in the Fall, will extend your swimming season then also.
The only hassle with these solar swimming pool covers is carrying them off and keeping them during the day. Since they are just one gigantic sheet, they are tough to handle. You can purchase a giant roller to roll up the sheet, but they're costly.
Although they're an"eye-sore" and sometimes a pain to move around and shop, they're well worth the investment (usually $100 or so) make them do a excellent job in heating the water up to a bearable temperature.
Bottom line – a solar swimming pool cover is a must if you would like to get swimming sooner or simply want warmer water.