How to Winterize an Above Ground Pool

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How to Winterize an Above Ground Pool
Image credit: Jonathan Hogue, Wikimedia

You have enjoyed swimming in your pool during the hot, steamy summer, but all things must come to an end. When fall arrives, you need to do a little more maintenance than usual to get your pool ready to store for the winter.

1. Test water

About a week before you close your pool for the winter, check the chemical levels to make sure they’re where they need to be. Below, we list where most of them should fall, but you should always check the manufacturer’s guide to see what the levels are for your particular pool.

If any of your levels are low, add the needed chemicals and retest a couple of days later. It’s essential that your water is chemically balanced when you close it.

Note: If you don’t want to purchase all these chemicals separately, you can buy a pool winterizing chemical kit that will have everything you need.

test water
Image credit: Airman 1st Class Melissa Flores, Ellsworth Air Force Base

Chemical levels


  • 2 – 7.6
  • pH is the level of acidity in the pool
  • If your pH is low, indicating highly acidic, add a base to lower it
  • If your pH is high, indicating low acid, add a pH increaser to it
  • A higher number is better for winter storage


  • 0 – 120 ppm
  • Alkalinity goes hand-in-hand with pH. If it’s low, the pH will be low. If it’s high, the pH will be high
  • Adjust alkaline levels the same way that you do pH levels


  • 175 – 250 ppm for vinyl; 220 – 350 for other surfaces
  • Too little calcium causes the pool material to begin breaking down; add a calcium increaser
  • Too much calcium makes your water cloudy; dilute with fresh, but not hard, water


  • 1 – 3 parts per million
  • Chlorine keeps your water sanitized
  • It’s recommended that you shock your pool just before closing
    • Fast-dissolving shock can be used immediately before covering the pool
    • Calcium hypochlorite, the typical shock, should be put in water the night before, since it takes eight to 24 hours to work

2. Clean

Clean your pool one last time before putting it to bed for the winter. Scrub the inside walls with a light detergent to remove any build-up. After you have the sides clean, get your vacuum out, and get it set up. These few minutes allow any removed build-up to settle to the bottom of the pool. Now, vacuum thoroughly one last time for the season.

You may be wondering why you need to clean the pool before closing it for the winter. Think of it as one of your dishes. You’d never put dirty dishes into your cupboard because they would get moldy. Your pool is the same way. Any dirt left in it can cause algae buildup.

men cleaning pool
Image credit: Peretz Partensky, Flickr

3. Lines

Pool lines are just like house plumbing lines. Water left in them will freeze, expand, and ultimately cause them to burst. Blow all the water in the lines from your skimmer back into your pool, and then plug them with expansion plugs to keep water out.

If you don’t know how to blow out your lines or don’t want to, purchase a swimming pool antifreeze to pour into them to keep them from freezing. Make sure the antifreeze you get is for pools. The kind you use in your car won’t work.

pool lines
Image credit: Brian Cantoni, Flickr

4. Skimmer

You have a choice to make when it comes to storing your skimmer. You can leave it as it is and not cover it. If you do that, lower the water level below the skimmer line, leaving enough space for water to drain out when it rains. If you choose this option, check it from time to time to make sure no debris gets stuck inside it.

You could also purchase a skimmer cover to seal it so nothing can get into it. Since it’s tightly sealed, you won’t need to lower your water level to below the skimmer line before covering it.

The other option is to remove the skimmer basket altogether and store it somewhere dry for the winter.

5. Filter and Pump

The pump

Remove your pump, chlorinator, hoses, and all drain plugs. Store the drain plugs inside your skimmer so you don’t lose them. Keep the pump, chlorinator, and hoses inside where it’s dry.

The filter

How you winterize your filter depends on what kind you have:

Sand Filters:

  • Set the multiport valve to “winterize”
  • If you have a sight glass or bleeder valve, remove them and store them in the basket
  • Allow the water to drain by removing the drain plug
  • Store outside
  • You can leave the pump outside if it’s too heavy to carry. The inside won’t freeze up and crack as long as the plugs have all been removed
  • Store inside
  • The best place to store your pump is in a dry location indoors. It has the best protection for your equipment and will make it last longer

D.E. (Diatomaceous Earth) Filters:

  • Drain it
  • Rinse fingers off
  • Leave the valves open
  • Store indoors

Cartridge Filters:

  • Drain it
  • Rinse the cartridge
  • Leave the valves open
  • Store inside where it is dry
pool pump and filter
Image credit: Bill Jacobus, Flickr

6. Lower water level – if needed

If you leave your skimmer in the pool without a skimmer cover, lower the water level to below the bottom of the skimmer. Leave enough room for any melting snow or rain to drain through the skimmer.

If you use a skimmer cover or remove the skimmer to store, you don’t need to adjust your water level at all.

low water pool
Image credit: Chris Grazioli, Flickr

7. Pool pillow

The pool pillow is an inflatable device that’s placed in the center of your pool between the water and the cover. It compensates for the weight of any ice or snow. Only inflate the pillow to 50% to 60% of what it will hold. The extra room gives the pillow cushion so that it won’t burst with a heavy snow or ice storm.

It also keeps dirty rainwater and debris off to the side of the pool to make clean-up easier in the spring.

8. Accessories

Wash all your accessories, from ladders to toys. Allow them to dry thoroughly and store them in a dry place for the winter.

pool accessories
Image credit: pompi, Pixabay


Winterizing your pool sounds like a pain, but it isn’t that difficult. It is necessary, though, to keep your pool lasting from year to year. If you follow all the steps to care for your pool, you will be glad you did when summer returns.