Close the pool for winter – but don't drain it.
In winter, the water in your pool is still your friend. Especially when properly winterized, it helps to protect the pool liner, keep it clean and prevent unnecessary damage from debris, harsh weather and other factors.
Drain the water down to no more than 6 inches from the bottom of the skimmer if you plan to use a standard floating winter cover. Use your pool filter, switched to the "Drain" setting, to empty the pool water.
You really only need one chemical (algaecide) to properly winterize a swimming pool. You need some other stuff to protect your pool from harsh winter conditions, but only one chemical to add when closing.
Yes, they can freeze solid. If temperatures reach below zero, swimming pools that are not circulating can freeze solid within a few days. If those low temperatures continue for several days, the ice sheet can increase in thickness by up to ¼” per day.
People often avoid covering their pool for the winter because pool covers are an additional cost. However, an uncovered pool will cost you far more over the span of a few short years than a simple pool cover. For one thing, an uncovered pool will become a catch-all for leaves and debris.
Even with proper and regular pool maintenance, it's often necessary to drain your pool — completely or partially — every 3-5 years. Draining your pool often isn't necessary, especially if you're following a proper and regular maintenance program.
An uncovered pool will lose water in the winter to evaporation in the same way it does during the summer. But the water loss is only about a quarter-inch on average during a 24-hour period when the pool is not in use. An uncovered or covered pool can have problems in the plumbing lines or pump.
When a gunite pool is left empty, its hydrostatic valve allows water beneath the pool to drain into the pool itself. Without a hydrostatic valve, an empty gunite pool may float on top of the underground water. All or part of an empty pool may pop out of the ground several inches or several feet.
On inground or indeck spas, you must also place a tarp or Winter Spa Cover over the hard thermal cover. Placing the Winter Cover over the hard cover and laying swimming pool type water tubes around the perimeter of the spa on your decking will keep any rain water from getting into your spa over the winter.
Most experts recommend waiting at least until temperature drops below 65 degrees Fahrenheit (18 degrees Celsius) to winterize your pool. However, if you can wait longer until your pool is below 50 degrees Fahrenheit (10 degrees Celsius), you will have a much lower risk of problems occurring.
Generally, pool water needs to be replaced once every five to seven years. This should be done during mild weather so that your pool surface is not at risk from strong sunlight and heat. Your pool maintenance company can recommend when it is time to drain your pool.
Because of these temperature parameters, the best time to year to drain a pool is usually in the spring or fall. Spring can be a good option, because the fresh water will then be ready for summer swimming.
Once water is removed (and subsequently, the interior hydrostatic pressure), if there's an influx of groundwater, it will push the pool up and out of place. As a general rule, you shouldn't keep any pool empty for longer than it needs to be. Get the work done that you needed to do and refill it as soon as possible.
Chlorinated and non-chlorinated pools freeze at the same temperature. However, salt water pools will freeze at a slightly lower temperature. It should also be noted that above-ground pools will generally freeze at a higher temperature than inground pools.
If you don't trust your well, it will cost about $400 to fill a 20,000 gallon pool using a good water company that will deliver drinking water. Be careful, some water delivery people will back up to a local pond to fill up.
By simply adding algaecide to your water prior to closing, you can prevent algae growth from occurring during the cold, winter months which makes for an easier opening in the spring. You can apply algaecide directly to the pool water and allow the pump to continue to circulate for approximately two to four hours.
First, don't add everything at once, or add everything except the shock – which should be added separately, either before or after, by at least 8 hours. Second, add phosphate removers, enzymes or stain & scale chemicals before you lower the water level, so you can circulate the chemicals for at least 8 hours.
Several days before closing, shock the pool with a chlorine shock or non-chlorine shock, using at least 2 lbs per 10,000 gallons (follow package directions). Allow the chlorine level to return to 1.0-3.0 ppm before adding any winter algaecide or your pool cover.