Swimming pool heaters are a must for those who want to enjoy their pool during cool summer nights and beyond the regular season. Swimming pool heaters can be electric or run on natural or propane gas. Heating pumps are another mechanism used for heating, while solar heating systems are an energy efficient means to warm your pool's water.

The size and power required of a heater depends on the amount of water in the pool, as well as environmental conditions like air temperature. Different heaters are often geared specifically for inground pools.

Most heaters are measured by BTUs (British Thermal Units). BTUs express the energy needed to increase the temperature of water by one degree (Fahrenheit). Most units are offered between 75,000 BTUs and 400,000 BTUs - the higher the BTU amount, the quicker the water can be heated. And, of course, the higher the BTU output the more the heater will cost!

Heat pumps are sometimes used in pools. They can be energy efficient and although purchasing one seems like a large investment at first, their energy efficiency can be reflected in their lower energy costs.

Heat pumps essentially extract heat from the air warmth from the air and transfer the heat the water in a pool. A drawback of the heat pump is that it takes longer than a heater for the water to reach optimum temperature.

For an environmental alternative, there are also solar heating options available. Most solar systems use solar panels by collecting natural energy from the sun to heat the pool's water. Solar systems are used continuously and are dependant on the weather but have extremely low (if any) energy costs.

Thermostats placed in a pool are great for monitoring the pool's water temperature and will help you monitor to ensure that your pool's heater is functioning properly.

Based on the current energy costs, electric heaters are considered to have the highest energy cost followed by propane heaters. Solar heating systems use very little energy, while a natural gas heater's energy costs are about half compared to a propane heater.