How to Winterize An Above Ground Pool

As the weather begins to cool down and the leaves start to change color, you may find yourself needing to winterize your above ground swimming pools. This process can seem daunting, but we’re here to help. Follow these simple steps and you’ll be ready for swim season in no time.

It’s certainly not fun when summer comes to an end. But if you follow the proper steps to close your above ground swimming pool, you can do it in just a few hours and enjoy a worry-free winter.

When to Winterize Your Above-Ground Pool

Depending on your location, your closing times will differ. As a general rule of thumb, if the average temperature drops and remains below 65°F (18°C) during the off-season, it’s best to wait until the temperature reaches that point to close.

Leaving your pool open until the cold weather sets in has several benefits. For one, algae and other organisms need warmth to thrive, so cold temperatures can help keep your water clearer.

Additionally, you’ll have more time to clean, test, and balance your pool before you close it up for the season. So if you’re looking to extend your pool’s lifespan and keep it clean and healthy, consider leaving it open a little longer this year.

If you live in an area where the temperatures rise above 65°F (18°C) for a few days during the winter, you can take advantage of the warm spell to test and balance your water chemistry. These tweaks will help you keep your water clean and clear until spring returns.

Steps to Winterization: How to Do It

Frigid winters can be tough on all kinds of swimming pools – but with the right gear and preparation, you can make sure your pools above ground is ready to last for years to come. By investing in a good cover and keeping it clean, you’ll be able to protect your pool from the worst of the winter weather and ensure that it’s ready for swimming as soon as the weather warms up again.

  • Collect Your Pool Closing Essentials
  • Clean Your Pool One Last Time
  • Test and Tweak Your Water for Winter
  • Add Winterizing pool Chemicals
  • Clear and Store the Lines
  • Protect Your Skimmer
  • Winterize The Filter and Pump
  • Clean and Stash Your Accessories
  • Lower the Pool Water
  • Install the Pool Pillow
  • Install the Pool Cover

1. Collect Your Pool Closing Essentials

Make sure you have the following supplies before winterizing your swimming pool:

  • Above ground swimming pool skimmer cover
  • Expansion plugs
  • Return line plugs
  • Above ground pools winter cover
  • Cover winch and cable
  • Cover clips
  • Winterizing closing chemical kit or pH increaser, Alkalinity increaser, Calcium hardness increaser, Pool shock, and Algaecide
  • Clarifying enzyme supplement
  • Water bags 
  • Swimming pool antifreeze (if necessary)
  • Pool air pillow
pool air pillow
Size4-Foot by 8-Foot

2. Clean Your Pool One Last Time

The off-season is the perfect time to give your winter pool a good clean. Make sure you best pool vacuum for algae the entire pool, brush down the walls, and skim the surface before you winterize. This way, you can start the next season with a clean slate – and a clear conscience.

winterize an above ground pool

A little preparation now will save you from some potentially nasty surprises when you open your pool next spring. A clean automatic pool makes it much easier to properly balance your water. It also ensures nothing is left behind to feed algae or mold that might develop during your pool’s long winter’s nap.

Pool Brush
ColorLight Green, Black
Handle MaterialAluminum

3. Test and Tweak Your Water for Winter

Open or closed, keeping track of your pool’s water chemistry is key to maintaining a healthy pool. Test your water before you close for the season to ensure that your pool is in good condition.

You can test the water’s chlorine levels yourself with test strips or a water testing kit for a little more accuracy. If you want the most accurate results possible, you can also take a water sample to your local pool store and have them test it for you.

pool test kit

You want your pH to be between 7.4 and 7.6, and your alkalinity to be between 100 parts per million (ppm) and 150 ppm, with 125 ppm being ideal. Your calcium hardness should be between 175 ppm and 225 ppm, and your chlorine should be between 1 ppm and 3 ppm. 

If you’re using a different sanitizer, just make sure it’s at the proper level. Since you won’t be adjusting the water balance during the off season, it’s better to start on the high side of these ranges when you close your pool because they’ll naturally decrease over time.

4. Add Winterizing Chemicals

Unlike some other things that need chemicals during the winter, like snow or poor old Bucky Barnes, the chemicals you add to your above ground pool during closing are there to help it during the cold season.

It’s important to balance your water when winterizing an above ground pool because balanced water is less likely to cause damage to your pool liner and other components.

Use a Winter Closing Kit

If you’re not feeling up to the task of breaking out your lab coat and beakers, grab a winterizing chemical kit for your above ground pool. Following the directions on the label will have your pool ready for winter in no time.

pool kit
Product Dimensions13.5 x 8.8 x 8.7 inches
Item Weight14.26 pounds

Adjust the Alkalinity

Alkalinity is the measure of carbonates, bicarbonates, hydroxides, and other alkaline substances in water. In simpler terms, it’s the pH level of water. Alkalinity is important to monitor in order to pool maintain balanced water. 

There are a couple of ways you can adjust your water’s alkalinity. You can increase it by adding a base, such as an alkalinity increaser or sodium bicarbonate. Or, you can decrease it by adding muriatic acid. Just remember, the ideal range for alkalinity is 100 to 150 ppm. 

It’s also important to note that a higher level is better when you’re winterizing. And always remember to adjust alkalinity before pH.

Pool Alkalinity Increaser
BrandIn The Swim
Item Weight51 Pounds
Item FormGranular

Make Sure the pH is Perfect

The pH level of your pool water is a measure of how acidic or basic it is. The lower the level, the more acidic the water is. The higher it is, the more basic the water is.

If your water is acidic, add a base to lower the acidity. If your water’s too basic, add a pH increaser to bring it into proper balance.

Remember, you’re shooting for a pH in the range of 7.4 to 7.6. And as with alkalinity, a higher level is better when you’re winterizing.

pH Increaser
BrandIn The Swim
Item Weight51.3 Pounds
Item FormGranular

Shock The Pool Before You Close

If you want to make sure your pool is sanitized and ready for winter, add some pool shock to the mix. Just consult the directions for each product to make sure you’re adding the right amount for your pool’s capacity.

pool shock

And since you’re closing the pool, you can use a fast-dissolving shock before you put the cover on instead of using a typical calcium hypochlorite shock that takes anywhere from 8 to 24 hours to work.

Chlorine Shock
Item Weight24 Pounds
Product BenefitsKills Bacteria,Controls Algae

Add a Dash of Winter Algaecide

Adding an algaecide to your pool right before you close it for the winter can help keep algae from coming in and ruining everything. Just follow the directions on the back of the package for the proper dose.

You can also add a clarifying enzyme treatment to further reduce algae growth, liner stains, and contaminant build-up. This comes in either a bottle or a convenient ball or “pill” you puncture and add to the water, where they release their payload all winter to help you greet spring with a clear pool.

If you’ve ever struggled to get your pool ready for swimming season, or if you want to avoid that in the future, these tips can help.

pool algae
Product Dimensions10 x 3 x 3 inches
Item Weight2.57 pounds

5. Clear and Store the Lines

Ice expansion can wreak havoc on your pool lines, just like it can on your home’s plumbing. Even if winters are mild where you live, it’s still a good idea to clear and remove the lines, and then store them in a dry place out of direct sunlight. Letting them dry completely is crucial, otherwise you could end up with moldy lines come next season.

6. Protect Your Skimmer

When it comes to winterizing your pool skimmer, you have a few different options to choose from. The first step is to remove the skimmer basket and store it in a safe, dry place for the winter months.

Then, you can decide whether or not you want to cover your skimmer for the season. A winter skimmer cover is a plate that covers the entire skimmer, sealing out any potentially harmful elements. If you use one of these covers, you won’t have to drain your pool below the skimmer line, which can save you time and hassle.

automatic pool skimmer

If you choose not to cover your skimmer during the winter, be sure to keep an eye on it to ensure that water can drain out if it rains. Keep the bottom of the skimmer free and clear – don’t plug it up.

7. Winterize The Filter and Pump

Packing away your filter and pool pumps at the end of the pool season is a pretty easy process that shouldn’t cause you much concern.

The Pump

Draining your pool for winter? Don’t forget to remove the drain plugs from the pump, chlorinator (if you have one), and all the hoses. Store all the drain plugs in the pump basket so you can easily find them when it’s time to set up your pool again in the spring. And keeping the pump, chlorinator, and hoses indoors will help them last longer.

pool pump

The Filter

The method you use for winterizing your above ground pool will depend on which type of filter you have.

Sand: Set your multiport valve to “Winterize,” and remove the drain plug at the bottom to allow the filter to drain completely. If your multiport valve has a bleeder valve and a sight glass, remove those too, and store them in the pump basket for easy retrieval next season.

If you have a cartridge filter, remove the cartridge and rinse it with a hose. Store the cartridge in a plastic bag with some water in it to keep it from drying out.

Bring your filter indoors for winter storage to avoid any potential damage from freezing temperatures. If the weight of the sand makes this too difficult, you can leave it outside as long as you remove all the drain plugs. This way, if any water or condensation builds up inside the filter tank, it won’t crack it.

8. Clean and Stash Your Accessories

As you close your pool for the winter, don’t forget to take care of your above ground pool ladder, toys, and any other accessories. If you leave them in the pool, they could get damaged or rust, which can cause serious problems for your pool.

To avoid this, gather up all your accessories and clean them with a multi-purpose pool surface cleaner. Let them dry completely, then store them in a clean, dry place out of direct sunlight until spring.

9. Lower the Pool Water

When it comes to winterizing your above ground pool, one question you might have is whether or not you need to drain any water. The answer to this question depends on how you plan on protecting your skimmer during the winter months. If you’re worried about freezing and cracking, and you don’t use a winter skimmer cover plate, then it’s best to drain the water level below the skimmer and returns.

On the other hand, if you do use a winter skimmer plate, you can simply remove the hose from your skimmer so it can drain properly, then install the plate. This way, you won’t have to drain your pool at all. Keeping the water level at its normal level is actually better for your winter cover.

If you have a solid cover, you can protect it from damage by draining water off the cover with a pump or siphon. This will keep the cover from getting too much pressure when rain water and snow collect on top.

10. Install the Pool Pillow

Knowing how to close an above ground pool means you’re one step closer to being a pool pro! In cold climates, placing a pool air pillow – also known as an ice compensator – under the cover protects the sides of the cover and the walls of your pool from damage. By doing this, you’re not only prolonging the life of your pool, but you’re also making sure that it’ll be in tip-top shape when it comes time to open it back up again.

Inflating an air pillow to around 50% or 60% of its capacity before covering your pool will help preserve it during the winter. This will allow the pillow to compress without immediately popping after the first substantial snowfall, and will make spring cleaning much easier.

Inflate the air pillow and secure it in the center of the pool using a rope or an accessory. Some pillows also come with built-in grommets to allow you to secure them on all four corners for easy centering.

11. Install the Pool Cover

Almost done! Place the winter pool cover over your pool—and the air pillow—and secure it by using the cable and winch, or a combination of winter cover clips and a cable.

Sometimes, more really is more. A combination of winter cover clips and a cable and winch will ensure a snug fit and give you greater peace of mind. If your pool has a walk-around deck, you can also add water bags to help secure your cover.

To avoid any damage to your liner, only use materials that are specifically designed for securing pool covers, such as bricks, stones, or winter cover clips. Do not use anything else that might damage your liner if it were to fall into the pool.

Keep an eye on your pool cover throughout the winter and do your best to keep it dry. An above ground pool cover pump can help remove excess water and keep your pool cover in good shape.

Pool Cover Pump

FAQ Winterize An Above Ground Pool

Should I completely drain my above ground pool for winter?

You’ll need to keep the water level low with a pump or siphon to protect your pool cover from water damage. Never drain an above ground pool completely when winterizing as it will cause your vinyl liner to dry out and shorten its lifespan.

How do I winterize my above ground pool without draining water?

A winterizing chemical kit can help keep your swimming pool’s water clear and blue for the upcoming season. You’ll want to lower the water level to just below the skimmer’s mouth before winter sets in. This removes the water from the skimmer’s throat, which could easily sustain damage if left there to freeze over winter.

Do you have to drain pool below skimmer for winter?

In order to prevent your lines from freezing and cracking, you will need to drain the water level down below the skimmer level. This will allow you to properly winterize your lines and prevent any potential leaks.

Are pool winterizing chemicals necessary?

When winterizing your swimming pool, you really only need to add one chemical – an algaecide. Although you’ll need some other supplies to protect your pool from the harsh winter conditions, the algaecide is the only chemical you need to add when closing.