Guide · 26 October 2026

Above-Ground Pool Winterizing: The Closing Checklist

Learn how to winterize above ground pool step by step, from water balance and skimmer plugs to the winter cover and air pillow, for a cleaner spring opening.

If you want to know how to winterize above ground pool equipment without a spring full of repairs, treat closing as one job with a clear order. You clean the water, balance it, protect the openings, drain the equipment, and then put the cover on. Skipping a step is how owners end up with stained liners, cracked fittings, or a cover full of dirty water in April. This above ground pool closing checklist follows that order for a steel wall pool, a metal frame pool, and a soft sided pool that your manual says can stay up over winter.

Before you start, read your pool manual, your filter manual, and your winter cover instructions. Soft sided and seasonal frame pools are the exception here. Some need to be drained, taken down, and stored indoors where winters freeze, while others are built to stay up when closed correctly. Your manual settles that question, how far to lower the water, and which plugs fit your skimmer and return. If you are still comparing covers or other closing gear, you can browse pool brands on our brands directory before you buy anything you do not already have.

Pick your closing weekend and gather supplies

Close too early and warm water sits under the cover for weeks, which gives algae a head start. Wait too long and a sudden freeze can catch a pump, a hose, or a skimmer full of water. Many owners close when water temperatures are consistently around the low to mid 60s degrees Fahrenheit or below, a timing guide described in this above ground pool closing guide. Watch your local forecast for a stretch of cool days rather than one cold night, and give yourself a full afternoon.

Gather everything before you touch the water. You will want test strips or a liquid test kit, a brush, a skimmer net, and a vacuum, plus chlorine shock and a winterizing kit or winter algaecide, following the labels for your pool size. For the cover side of the job, you need a winter cover matched to your pool shape and size, the cable and winch that came with it, and cover clips or weights if your yard gets wind. Keep a skimmer plug or skimmer plate and a return plug on hand, plus a winter pool cover air pillow if you live where the water freezes. A cover pump or a simple siphon helps later with rain and meltwater on a solid cover. Put small parts in a labelled storage bin as you remove them.

Clean the pool and balance the water

Start with the cleanest water you can get. Skim the surface, brush the walls and the floor, and vacuum up leaves, dirt, and fine debris, especially around the skimmer and the return, where debris collects and stains form over winter. If you can see algae, treat it and run the pump until the water is clear before you close. Covering green water usually leaves a worse cleanup in spring, and the stain may stay on the liner long after the water clears.

Clean the filter before closing as well. Backwash a sand filter, or hose down a cartridge and let it dry. Clean the skimmer basket and the pump basket, and take any unused chlorine product out of the chlorinator.

Test the water before you add any closing chemicals. Balanced water protects the liner, the fittings, and the pool surface while the pool sits unused. Backyard City Pools lists pH 7.2 to 7.6, alkalinity 80 to 120 parts per million, calcium hardness 175 to 250 parts per million, and chlorine 1 to 3 parts per million as the closing ranges to aim for (Backyard City Pools winterizing steps). Adjust in small steps and retest. Your pool manual and the chemical labels override any generic range if they disagree.

Once the water tests in range, shock the pool and run the pump long enough to circulate the shock through the whole pool. Follow the shock label for your pool volume, and give it time to mix before you add anything else. Add winter chemicals separately, one at a time, and broadcast them into the pool as the label directs. Never mix chemicals together in a bucket unless a label tells you to, and avoid pouring chemicals straight onto the liner, where they can bleach or stain one spot.

Protect the skimmer, the return, and the water level

Slow down here, because this is where expensive mistakes happen. One approach lowers the water below the skimmer and the return openings. The other keeps the water higher and seals the openings with a skimmer plate or plug and a return plug. Read your cover instructions before you choose, because some covers are sized for a lowered water level, while others expect the skimmer to be plugged.

Whatever you choose, do not drain the pool completely. Backyard City Pools warns that you should never completely drain an above ground pool because it can collapse (Backyard City Pools winterizing steps). The water left in the pool supports the walls and holds the liner in place. Draining too far can pull the liner away from the wall, leave wrinkles, or put stress on the frame that shows up as a lean or a buckle in spring. If you are lowering the level, stop where your manual says to stop, and check the level with a tape rather than guessing from the skimmer opening.

Fit the skimmer plug, plate, or return plug carefully and check that each one seats fully. A plug that sits crooked can let water seep into a fitting all winter, and that trapped water is what freezes and cracks plastic. Wipe grit off the sealing surfaces first, and keep spare plugs in your storage bin with the drain plugs and clamps.

If your pool has hard plumbing rather than flexible hoses, clear water out of the lines now with a shop vacuum on the blower side or an air compressor used gently, then plug the openings. For flexible hoses, disconnecting and draining them usually does the job. Use pool safe antifreeze only if your manual or a product label calls for it, and never use automotive antifreeze in pool plumbing.

Drain and store the pump, filter, and salt cell

Turn off power to the equipment before you disconnect anything. Remove the hoses from the pump, the filter, the heater if you have one, the chlorinator, the salt system, the skimmer, and the return fittings. Drain every hose fully, coil it loosely, and store it indoors where it will not freeze or kink. Hoses left hanging on a fence over winter tend to crack at the bends.

Take the drain plugs out of the pump, the filter tank, and any other equipment that holds water. Let each piece drain completely, and wipe down the pump basket and the filter parts while you have them open. Backyard City Pools suggests placing all drain plugs in the pump basket for storage, so they stay with the equipment they belong to (Backyard City Pools winterizing steps). If you use your own storage bin instead, put a note in it that says which plugs go where.

For a cartridge filter, clean the cartridge, let it dry fully, and store it indoors. For a sand filter, backwash it, drain it following the filter manual, and leave the drain plug out. For a saltwater pool, remove the salt cell and store it following the salt system instructions. Ladders, steps, solar covers, floats, toys, and cleaners come out too. Wash them, dry them, and store them indoors.

Put on the cover and air pillow, then check through winter

In a freezing climate, a winter pool cover air pillow does a specific job. When pool water freezes, it expands and pushes outward against the walls. A pillow gives the ice a softer spot to press into, which takes some pressure off the wall. Backyard City Pools notes that air pillows are a good idea in colder climates, with the water freezing inward on the pillow instead of outward against the wall (Backyard City Pools winterizing steps). Rainwater will still settle around a pillow on the cover, so you will still need a cover pump.

Inflate the pillow only partway, unless its own instructions say otherwise. Above Ground Splash advises inflating a pool pillow to around 60 percent to 80 percent, because a pillow inflated too hard has less room to compress when ice presses against it (Above Ground Splash winterizing guide). Tie it near the center of the pool so it stays put while you spread the cover, and recenter it if it drifts to one side during installation. A pillow bunched against the wall does little good, and it can leave a low spot where water collects.

Spread the winter cover evenly over the pool, black side down for a standard winter cover, with overlap all the way around the wall. Thread the cable through the loops or grommets and tighten it with the winch until the cover sits snug. In a windy yard, cover clips, stretch wrap around the top rail, or cover weights can cut down on lift. If your pool has a deck, wall bags placed end to end around the edge can hold the cover down. Backyard City Pools advises filling wall bags 3 quarters full with water, and warns against overfilling because the bags could burst when the water inside freezes (Backyard City Pools winterizing steps). Never use bricks or concrete blocks to hold a cover, because they can damage the cover and the wall if they shift.

A leaf net over a solid cover helps if your pool sits near trees. Put the solid cover on first, lay the leaf net over it during heavy leaf fall, and lift the net away with the leaves before they rot on the cover. Keep a cover pump in the center of the cover when water builds up, because heavy water stretches the cover and pulls at the edges. Pump after rain and after thaws, with the hose draining away from the pool base.

After a major thaw, walk out and look at the cover, the cable, and the edges. A cold climate guide recommends planning quick winter checks after major thaws to confirm the cover is taut and the cable is still seated in its groove (GeekMamas cold climate winterization guide). Pump off standing water before it gets heavy, and refasten any section that has blown loose before wind turns a small gap into a torn cover. In spring, clear debris off the cover before you pull it, so grit and dirty water do not wash into the pool.

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