How to Winterize an Above-Ground Pool

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Properly closing your above-ground pool for the winter protects your investment from damage that can occur during the off season regardless of where you live. While the closing process is similar for every pool owner, winterizing requires extra steps, and which steps you need depend on your climate. In addition to regular maintenance, learning how to effectively winterize an above-ground pool is essential for its long-term well-being.

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Why It’s Important to Close Your Pool Properly

There are some places on the planet where a pool never needs to be put away for the season. However, many of us live where the temperature can dip to freezing or stay below freezing for a period, or where it's simply too cold to swim but not necessarily cold enough to worry about frozen pool components. Myles McMorrow, owner of Pool Services of NOVA in Virginia, tells Hunker, "Without proper winterization, you get pipes bursting under the deck and (expensive) damage to the equipment."

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Proper closing of your above-ground pool is essential, whether that just means less work in the springtime or avoiding damage from freezing weather. Here are a few other things that can occur if you don't close your above-ground swimming pool properly:

Algae Growth Can Occur

In warm climates where freezing temperatures aren't a daily concern, pool water must be properly treated for winter, even when the pool is under a winter cover. Failing to do this leads to the growth of algae and potentially harmful bacteria, which can take over due to a lack of proper chemical balance. Cleaning up the mess is quite a chore when reopening the pool in the springtime.

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Components May Freeze

Frozen water pipes can lead to burst pumps and pool filter casings, and pool heaters can be destroyed by ice forming inside them if excess water is present when the temperature falls below freezing. When water freezes, it expands with tremendous force. If there's no void for that ice to fill, such as inside your pool components, it simply pushes until it relieves its own pressure by breaking open the compartment. Although PVC pipes aren't costly to replace, all other freeze damage will set back your wallet a generous amount.

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Structural Damage Can Occur

For the same reason that pipes and components can break in freezing weather, your pool can suffer damage if water freezes inside your skimmers. Next spring, you may also find yourself trying to repair pool liner leaks or structural damage caused by shifting ice, improper water levels, or excessive pressure on the pool walls.

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When to Close Your Above-Ground Pool for the Winter

Algae can grow in a covered above-ground pool at temperatures as low as 65 degrees Fahrenheit, continuing down to 40 degrees. For this reason, wait until the daily high temperatures stay below 65. The average time of year that temperatures drop to pool-closing levels depends on where you live.

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When To Close Your Above-Ground Pool for Winter

U.S. Region

Month

Northeast

October

Midwest

September

Northwest

October

Southeast

Not necessary due to climate

Southwest

December

Do You Need to Close an Above-Ground Pool in a Warm Climate?

In places that remain warm enough to enjoy swimming all year, there's no need to close an above-ground pool for the winter. If the climate in your area reaches temperatures that are well above freezing, but are too chilly for using your pool for an extended time, you'll want to close your pool for the season. You can perform an abbreviated version of pool closing if you wish.

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McMorrow tells Hunker, "There's no winterization in places down South. In places like Florida or California, you can just put the pump on low."

However, the amount of effort you invest in properly closing your pool could significantly affect how much work it takes to make it swim-ready again when the weather improves. Closing your pool in a warm climate involves fastening an appropriate pool cover to keep out debris and maintain safety. Adding algaecide and stain and scale remover, and balancing the chemicals are other important steps that will keep the pool clean and easy to start up again for the next swimming season.

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Winterizing Above-Ground vs. In-Ground Pools

Winterizing procedures and tasks are nearly identical for in-ground and above-ground pools, with a couple of important variables. First, your winter cover must be appropriate for the type of pool you own and the climate in which you live. In-ground pool covers anchor to the perimeter of the pool, while covers for above-ground pools are stretched over the pool and secured to the walls.

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Second, above-ground pools can freeze solid during extremely cold weather. While in-ground pools can freeze, the ground offers some insulation that above-ground pools do not have. Also, in-ground pools are better at handling the pressure of expanding ice. To protect your above-ground pool from ice damage, place a pool pillow (a vinyl pillow filled with air) underneath the pool cover to provide an air space where ice can expand instead of breaking the pool wall.

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When to Call a Professional to Close an Above-Ground Pool

None of the steps involved in closing an above-ground pool are particularly difficult. The tricky part is ensuring that each step is performed correctly and thoroughly. If this is the first winter that you own your pool, calling in a professional to complete the first seasonal closing is a great way to learn about the procedure.

If your pool winterizing runs into unexpected trouble along the way, if your pool chemicals don't seem to act as they should, or if the pool is unexpectedly stained or full of debris, call a pro for assistance instead of taking the risk of potential damage. A local professional will also know about regulations regarding the release of chlorinated water into the sewer system if you need to drain the pool more than a little for any reason.

Many owners who can close a pool themselves hire a professional to do the job each year simply for peace of mind in knowing that everything is done correctly.

Things You'll Need

How to Winterize an Above-Ground Pool

1. Remove the Ladders and Toys

Just so that nothing gets in your way while winterizing your pool and so nothing is forgotten, start with the basics. Remove toys, ladders, and other pool accessories, let them dry completely, and stash them away in a dry location until next year.

2. Clean the Pool

Even if your robotic pool cleaner has been working hard all summer, a manual deep cleaning of your pool is recommended before winterizing it to avoid any surprises next spring. Vacuum the pool, scrub the walls with a brush, and remove any debris from the surface of the water with a skimmer net. A clean pool allows the winterizing chemicals to perform at their best.

3. Balance the Water

Check your pool's water chemistry using a pool testing kit, and make final adjustments as needed to balance the water. Aim for alkalinity of between 100 and 150 parts per million (ppm), a 7.4 to 7.6 pH level, and 175 to 225 ppm calcium hardness. The chlorine level should range from 2 to 4 ppm, and higher is better without exceeding that range.

4. Add Winterization Chemicals

If you purchase a winterization chemical kit, you'll find that it includes an algaecide and a stain preventer, among other chemicals. Follow the instructions in the kit for your size of pool, or add separate algae and stain prevention chemicals as their directions indicate.

5. Shock the Pool

Shock the pool by consulting the instructions on your pool shock product. To speed up the process, use a fast-acting, chlorine-free pool shock.

6. Reduce the Water Level

Remove the skimmer basket, and let it dry to get it ready for storage. Siphon or pump out enough water to lower the water level to 3 or 4 inches below the bottom of the pool skimmer. Alternatively, you can install a winter skimmer plate and skip removing water from the pool.

7. Add a Winterizing Pill

Floating a winterizing pill in your above-ground pool will keep your pool water clear and prevent stains and scale buildup all winter.

8. Remove the Filter, Lines, and Plug Inlet Fitting

Completely drain the pool pump and chlorinator by removing the drain plugs. Remove the cartridge filter and give it a quick rinse. Remove and drain the water hoses or lines. Replace the water inlet fitting with a winter inlet plug. Keep the inlet fitting with the other drain plugs. Let all of the removed parts dry in preparation for storage.

9. Add Air Pillows

Create an air space for the expansion of ice and provide pool cover support by floating at least one air pillow in the pool water. How many you need depends on the size of your pool and the pillows. A 12-foot-diameter round pool will only require one 4 x 5-foot pillow, while a 15 x 30-foot oval pool will need at least a 4 x 8-foot pillow.

10. Install a Winter Cover

Many winter covers for above-ground pools come with a winch (a tool that helps to tighten and loosen pool covers) and cable for installation. If you don't have a winch, have a partner assist you in putting on the pool cover. Once it's stretched over the pool, secure it with frame clips or another anchoring method.

11. Store the Pool Equipment Safely

Store all of the removed pool parts, as well as any robotic cleaners, indoors where they will stay dry and not be subject to freezing temperatures.

When Can You Reopen Your Above-Ground Pool?

Once your pool is closed for the year, you can start dreaming of the day when you get to reopen it next year. When spring arrives, wait for daytime temperatures that are consistently above 70 degrees Fahrenheit, and open the pool a couple of weeks before you intend to go swimming. Here are the typical opening months around the country, which can vary depending on how the spring unfolds. Remember that sooner is better than later.

Typical Pool Opening Time by Region

U.S. Region

Month

Northeast

April-May

Midwest

May

Northwest

April

Southeast

Not necessary due to climate

Southwest

March

Signs That You Didn’t Winterize Your Above-Ground Pool Correctly

Unfortunately, other than a noticeable problem with the pool cover installation, signs that your pool hasn't been winterized correctly will go largely unnoticed until it's too late. Cracked water lines or water dripping from inside your pump or other mechanical components indicate damage from improper winterization. Ice damage to the pool itself may become apparent as soon as the water begins to thaw, revealing leaks or other problems.

Less harmful things, such as algae blooms or staining, may be evident in the spring, meaning you didn't winterize your swimming pool correctly, but you avoided the expensive potential outcomes.

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