We sell and install heaters to keep your pool warm even when the temperature drops.
A gas fired heater will heat your pool and maintain a temperature to your desired setting. You should expect about a 1 degree temperature rise per hour with this type of heater if it is sized properly to your pool. This is great for those who heat their pools up on a Friday morning to have it ready for the weekend. Most gas fired heaters have an efficiency rating at 82%.
A heat pump will take longer to get to temperature and does not perform well in really cold temps (40 degrees or less). However they will maintain a temperature more efficiently. A heat pump can reach 300% efficiency under the right conditions.