How to Winterize (close for winter) Your In Ground Pool

Winter Pool Cover Blue

Covered Pool, Ready for the Winter

A Step-by-Step Guide to Closing your In Ground Pool

Step 1

Before closing your pool for the season, make sure your pool’s water is chemically balanced.  Adjust levels if necessary.  Water that is chemically balanced protects the pool from corrosion and scale buildup that can develop during the off season.  Ideal chemical levels are as follows:

  • pH: 7.2 – 7.6
  • Alkalinity: 80 – 120 parts per million
  • Calcium Hardness: 175 – 250 parts per million
  • Chlorine: 1 – 3 parts per million

Step 2

Remove all deck equipment.  This includes ladders, rails, furniture, etc.

Step 3

Clean the floor and sides of your pool with an appropriate brush and then vacuum the loosened dirt.  Dirt and debris left in a pool for extended periods of time can cause staining.

Step 4

Add winterizing chemicals by broadcasting them into the deep end of the pool.  Winterizing chemicals help set the quality of your pool’s water during the winter months, which helps protect the cover, liner and pool walls.

Step 5

Clean the filter, skimmer, and pump basket. Remove any unused chlorine product from the chlorinator.  Cartridge filter elements and D.E. grids should be cleaned, dried and stored away.  If you have a sand filter,  backwash it at this time.

Step 6

Lower the water in the pool below the skimmer and the returns (where the water jets into the pool). Use an air compressor or shop vac (attached to the blower side of the vac) to blow water out of the system.  This forces air down the skimmer and through the plumbing.

Important: Never completely drain your swimming pool.

Step 7

Cap off return lines by using threaded plugs, or use expandable rubber plugs if your returns are not threaded.  Add anti-freeze by pouring it through the skimmer.  Use 1 gallon of anti-freeze for each 10 feet of distance from the pump to the pool.

Step 8

Remove all drain plugs from the pump,  filter tank, and other pool equipment.  Follow the manufacturer’s instructions for your specific equipment. Place all drain plugs in the pump basket for storage.

Step 9

Place an in ground winter cover over the pool surface, black side down. Some pool owners prefer to use safety covers rather than winter covers, especially if the home has small children or pets.

When using a winter cover, place water tubes end to end around the edge of the pool. Fill the water tubes 3/4 full of water (do not over fill because the water tubes could burst when the water inside freezes). Never use concrete blocks, bricks, etc. to secure the cover because they can damage the pool cover or the pool.

Step 10

Place a cover pump in the center of the pool cover to drain off excess water that will accumulate over time. This is very important because too much water on top of the cover can cause the cover to rip or pull the cover and water tubes into the pool, making for a very messy cleanup.

About Trey Collier

Grew up as a Military Brat. (Thanks Dad. Hats off to my Mom too as it took a special person to be married to someone in the military) Was a competitive swimmer in high school and in college. 11 years a Red Cross Volunteer, teaching kids & adults how to swim. ARC Water Safety Instructor and WSI Trainer, CPR Instructor/Trainer and Advance First Aid Instructor. Proud Dad of two beautiful girls.

13 thoughts on “How to Winterize (close for winter) Your In Ground Pool”

  1. Jonas

    It sounds like draining to below the returns is a safe choice, no matter what kind of pool you have. I would not worry about the pool light getting cracked during the winter. They are pretty strong.

  2. Steve Ladino

    Please tell me why there is no damage from freezing water in the pool but freezing in the skimmer box will cause damage.

    1. Trey Collier Post Author

      Good question. There could be damage to the pool especially a vinyl lined pool. Ice is water crystals. When it changes from a liquid to a solid it expands in volume. If the last place it solidifies is next to the liner, then it is possible for the “Expanding” crystals to poke hole into or cut the liner. If this is a possibility for your pool we recommend adding an air pillow. Ice will form all around the air pillow first, then under the pillow pushing it up as the last bit of ice forms.

      The above is less of an issue with fibreglass and gunite pools due to their strength of the wall.

  3. Bill

    in freezing climates how low do you drain pool when you have a pool light or does it not make a difference. My thought is freezing might crack the light nitch.

      1. Pat

        What do you mean by properly closed. If all the lines are blown out is that properly closed? The question is referring to the light and the niche. I’ve read the light should be removed from the niche and set on the top deck.

        1. Trey Collier Post Author

          Keep submerged during winter. This prevents the lens gasket from drying out. Keep the water level above the top of the lens and below the returns to avoid pressure from the pool surface ice sheet that forms during winter. You don’t want ice anywhere near the pool light. Often the pool light is deep enough, well below the ice layer if the pool builder in a cold climate did their job correctly.

          Alternate approach is to remove the light from its niche and let it hang to the bottom of the pool. Use a nylon cord to keep strain off the wire if it doesn’t reach to the bottom.

  4. Trey Collier Post Author

    Good question.

    I’m going to assume that you made sure there is a tight seal, because you were successful on the other lines. I’ll also assume that water is flowing back to the pool so we know there aren’t any obstructions to block the line.

    You might have more than one return. If so, you need to put in the plugs on all but one to blow out the line, then plug it up. Repeat on the other returns. There will ALWAYS be a little water left unless your vac is powered by a nuclear reactor! 🙂 So you may want to use some Pool Anti Freeze (which is Non Toxic) in those lines as a precaution.

    Of course there is the old fashion way, drain pool below return lines, Water drains out, then blow out, add antifreeze and then plugs and refill. <--- Last resort.

  5. Jon DeLisle

    I am having trouble blowing out the pool return lines. I was successful with the skimmer lines, the main drain, jacuzzi returns, and jacuzzi drain. I blew out the suction lines through the pipe opening inside the pump. I blew out the jacuzzi returns through a pipe opening in the filter but for some reason can’t get air to the pool wall returns. How do I blow these out? I’m so close to being done…please help. Thanks!

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