How to Winterize a Pool

Learn how to close and open an above-ground pool with these pool winterizing tips.

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Nothing beats the convenience of having a private pool in your own backyard. This guide will help you ensure each summer is as fun as the last by teaching you how to winterize a pool at the end of each season. A pool that is thoroughly cleaned with properly balanced water is much quicker and easier to open the following summer.

Tip: Wait until you’re sure it’s the end of swimming season before closing down the pool – around 65 degrees Fahrenheit and continuing lower.

Tools & Materials

How to Winterize a Pool

winterize a pool
Test and Clean the water

Tip: Follow these steps in order so that the chemicals you use throughout don’t negatively affect one another.

1. Eliminate existing water problems such as algae or cloudiness with the necessary chemical treatments.

2. Remove debris such as leaves and errant twigs or pine needles, then vacuum the pool and brush the sides.

3. Check the water pH – it should be between 7.2 and 7.6. The lower the pH, the more acidic your water is. Adjust as necessary using pH increasing or decreasing agents.

4. Test the alkalinity – during months of use, ideal pool alkalinity is 80 to 125 ppm, but in the off-season, it should be around 150. Alkalinity is the measure of substances in your water which act as a buffer to maintain a stable pH. Use low doses of acid to slowly lower the alkalinity over several days, or a total alkalinity increaser to raise it, as needed.

5. Check the water hardness – it should be around 200 to 250 ppm. “Hard water” will deposit calcium in your pool which could lead to a calcium buildup, whereas “soft water” will draw calcium from within the pool which could damage it as well. For hard water, diluting it with fresh water may help. For soft water, add calcium hardness increaser.

6. Add a large, off-season dosage of algaecide to the pool to prevent growth during the winter months.

7. Shock the pool with an off-season dosage of chlorinating shock product. You can use either a standard or fast-dissolving shock product.

8. A few hours after shocking the pool, double-check that chlorine levels are at 4 ppm or higher.

Plug up the pool

• Remove the eyeball fitting on your return line and plug it with a rubber plug and wing nut.

• Drain the pool about four to six inches below the skimmer then add a skimmer cover.

Winterize the equipment

• Remove the pool’s pump, chlorinator, hoses and any other equipment.

• Remove all drain plugs to completely drain the equipment.

• Bring all equipment indoors for storage over the winter.

• If you have a sand filter, set the multiplier valve to winterize. If there is no winter setting, set it between two positions and remove the plug at the bottom, letting the filter drain out.

• If you have a cartridge filter, drain it, rinse off the cartridge with hose or tap water, and store it indoors.

• DE filters should be drained, the DE grids or fingers cleaned, and the filter reassembled.

pool closing

• Blow up the air pillow and place it in the middle of your pool.

• Put on the pool cover and secure with winter cover clips.

• Remove the ladder and other deck equipment.

Pool Opening

open a pool
Clean and remove the pool cover

• Use a pool cover pump to remove water from on top of the pool cover and a soft broom or skimmer net to remove leaves or debris. Avoid using anything sharp that could damage the cover.

• Remove the cover, then lay it flat on the ground and wash gently with water (from a hose, not the pool) and a brush.

• Once the cover is completely dried, store in a covered container when not in use.

remove winter plugs and skimmer cover

Check the entire pool and remove coverings from all openings, including the return key and skimmer bucket.

reinstall the plumbing and equipment

• Reinstall the plumbing that was stored indoors, then reinstall the filter (if you use a cartridge filter.) Attach a hose from your skimmer to your pump, from your pump to your filter, then from your filter to your heater, chlorinator, or other equipment. If you have no other equipment, attach the hose directly to the return inlet.

• Turn the multiplier valve into the filter position

• Reinstall the deck equipment, including stairs and ladders.

Start the water pump and filter

Start up your water pump and filter and allow them to run for at least 24 hours before using the pool.

clean and test the pool water

• Remove any debris from the pool water that may have snuck under the cover during the winter.

• Add water to increase the water level as necessary.

• Test the pH, alkalinity and chlorine levels of your pool water. Ideal levels are: 7.2 – 7.6 pH, 80 – 125 ppm for alkalinity and 1 – 4 ppm for chlorine. Add chemicals as necessary to regulate the water composition levels.

• Vacuum the pool and re-test the water a few hours after you’ve added chemicals.

Tip: It is common to back backwash in sand and DE filters or to have to rinse off a cartridge filter or empty the skimmer baskets almost daily when a pool is initially re-opened after the winter. This is just your pool equipment removing debris that has built up throughout the winter. It should return to normal within a few days.