Pool Covers and Winterization

The easiest way to help keep your pool or spa in good repair is to properly cover it after every use, to both keep out debris and conserve internal heat. If you live in a cold-weather climate, it is imperative to properly winterize your outdoor pool and spa at the end of every season, in order to prevent catastrophic damage from ice.



Since the whole point of having a pool or spa in the backyard is to use it, most people don’t spend a lot of time thinking about not using it. That is to say, even though we care about the temperature and cleanliness of the water when we’re actually getting in, we aren’t ever nearly as concerned when we are getting out. Likewise, when you think about your pool, you probably imagine it under the shining summer sun, and not buried under two feet of February snow. The point here is that personal pool care is an ongoing responsibility, regardless of the relative weather conditions or the frequency of use, and the same is true of hot tubs and spas. Knowing how to properly cover and close a pool is essential for owners everywhere, and often can make the difference between water that is cold and murky, and a pool that is warm and clean.

 pool cover

All pool coverings have two basic functions: they keep heat in, and they keep other things out. An outdoor pool collects a significant amount of heat directly from the sun, as water is excellent at soaking up large quantities of solar energy – the problem is that when the sun goes down and the temperature drops, much of this accumulated warmth is evaporated away. Covering a pool at night will increase the average water temperature significantly, and (if the pool is artificially heated) will noticeably decrease any related power costs. And just as we want to keep all that warm water in our pools, we want to keep everything else out. Maintaining clean and chemically balanced water can be challenging enough just given the dirt and grime that collects during regular use, without Mother Nature sneaking anything else into the mix. The last thing any pool owner needs is to find himself fishing for twigs and squirrel droppings on Saturday morning.


The most common material for pool and spa covers is vinyl, which is highly effective at both absorbing external sunlight and trapping internal heat. Transparent, plastic “bubble” covers are also popular, and typically fare better at capturing ultraviolet rays during the day, but they do not retain warmth as quickly as their vinyl counterparts, which can benefit from extra layers of insulation. Pool covers sit on the deck and stretch over the pool, or – as is common with the “bubble” variety – float on top of the water itself. The vast majority of covers are manually stored, meaning they either fold or roll up, but mechanized reels are available to assist owners of larger pools, and automatic, built-in covers are an option for those who can stomach the cost. The price is high, but it sure is convenient to be able to open and close your backyard pool with the simple flip of a switch.

 bubble cover

For those owners who live in colder climates and maintain outdoor pools, there is the added responsibility of properly closing up shop for the winter. Known as winterization, this process is of critical importance in preventing the extensive structural damage that can be caused by extreme temperatures. In-ground pools need to have their pipes drained completely, their filter systems cleaned and unplugged, and their pump motors stored away. Most above-ground pools in freezing climates should be completely shut down for the winter, as ice buildups can weigh down, and eventually collapse, their external framing. In-ground pools and outdoor spas should also be provided a special, winter cover. These covers are more durable than the types intended for day-to-day use, and should be firmly secured to the deck, capable of withstanding the very worst storm that may arise. It is a good idea to leave one or more floating objects beneath the cover, which helps to prevent freezing, and many owners also choose to set a different “off-season” chemical balance, just before they close up.


If you own, or are considering owning, an outdoor pool or spa and are at all unsure about pool covers or winterization, it is best to get in touch with your pool technician and installer. They will be able to give you expert advice on the optimal cover(s) for your situation, as well as tell you exactly what must be done with your equipment in preparation for the winter.