Use of a swimming pool blanket during the coldest winter months is an essential part of a cost-effective pool heating strategy. The most popular pool blankets are similar to plastic air bubble packing material. To increase durability, the pool blanket’s plastic contains UV inhibitors and is two to three times thicker than the plastic used in air bubble packing material.
While you may read in various places that a “solar” pool blanket “traps” more solar energy than the pool’s surface alone, this isn’t really true. In reality, an uncovered pool surface absorbs slightly more solar energy than a pool blanket. The blanket material actually reflects more solar energy than water. However, this very slight disadvantage in solar energy collection is greatly outweighed by the pool blanket’s ability to keep heat already in your pool water from escaping. A swimming pool loses heat primarily through evaporation at the surface; a pool blanket blocks this evaporation.
How much of a difference can a pool blanket make during the winter months? In Florida, just keeping a blanket on your pool from late afternoon to mid-morning can reduce the cost of running a gas heater or electric heat pump by more than half.
Solar and heat pump pool heaters work best with pool blankets. A swimming pool heating system maintains a certain water temperature by replacing heat that the pool loses—mostly through evapotation at the surface. During the winter months, evaporative heat losses can become so great during the coldest weather that a solar pool heater or heat pump pool heater simply can’t keep up. This is because the amount of heat that each type of heater can add to your pool is limited by air temperature, wind and cloud cover. By reducing evaporative heat loss, the pool blanket substantially increases the number of days each year when the limited heating capacity of your heating system will result in a comfortable swimming temperature.
Additional advantages. A pool blanket will also provide you with two additional advantages. First, the blanket will keep debris out of your pool and make it easier to keep clean. This can be particularly useful during the fall months when trees are losing their leaves. And second, by reducing evaporation off your pool’s surface, a pool blanket can reduce how much you spend on replacement water and pool chemicals during the heating season.