Closing an Above-Ground Pool: Step by Step

Before my sister bought her house with the in-ground pool, she rented a place in Colorado with a 24-foot above-ground pool. The landlord left a page of notes. She skimmed them, pulled the cover on in October and figured that was enough. In April she found the skimmer housing split down one side, and the water underneath the cover was a dark, murky green.

She called me, a little embarrassed, and we walked through what went wrong. Water had stayed in the skimmer and froze. The pool had been closed in warm weather with no algaecide. None of it was hard to prevent. The next fall I flew up and we did it properly. Here is that routine, step by step, the way we still do it.

Why above-ground pools need a careful closing

Above-ground pools are simpler than in-ground pools in some ways. The pump and filter usually sit on the ground and connect with hoses, so you can take them inside. But the pool walls, liner and skimmer are more exposed to cold air, ice and wind.

A good closing protects against a few main risks:

• Freezing water in equipment. Water left in the pump, filter, hoses or skimmer can freeze, expand and split plastic parts.
• Ice pressure on the walls. A sheet of ice can push against the pool wall and skimmer. An air pillow under the cover helps absorb that pressure.
• Algae under the cover. Warm water, leftover debris and low sanitizer give algae a long, quiet season to grow.
• Cover damage. Wind can lift a loose cover. Standing water and snow can stretch or tear it.
• Liner damage. A vinyl liner can shrink and pull loose if the pool is drained too far. Most above-ground pools should never be fully drained for winter.

The fix, in order

Test first, add chemicals second. I start a few days before the cover goes on so the chemicals have time to work.

1. Pick the right week. Aim to close once water stays below roughly 65°F, but before the first hard freeze. Closing too early in warm weather is the most common reason for a green spring opening.
2. Balance the water. Test pH, alkalinity and calcium hardness. Adjust pH and alkalinity first, toward the targets in your test kit or pool manual. Balanced water is gentler on the liner and metal parts over winter.
3. Clean thoroughly. Skim leaves, brush the walls and floor, and vacuum. Empty the skimmer basket and pump basket. Anything left behind becomes algae food.
4. Shock, then add winterizing algaecide. Shock according to the label and run the pump overnight. Many closing kits say to wait until chlorine drops back toward normal before adding algaecide. Follow your kit’s directions and add each product separately.
5. Clean the filter. Backwash a sand filter, or remove and hose off a cartridge. A clean filter makes the spring start much easier.
6. Lower the water if your cover requires it. Many above-ground owners lower water a few inches below the skimmer and return. Some closing kits use a skimmer cover plate instead, so the level can stay higher. Follow your pool and cover maker’s guidance.
7. Disconnect and drain the equipment. Unplug the pump and turn off power. Disconnect the hoses, drain the pump and filter, and remove their drain plugs. Store the pump, filter parts, hoses and any chlorinator in a dry, protected spot, following each manual. Keep the drain plugs in the pump basket.
8. Plug the skimmer and return. Install a winter skimmer plate or plug, and a winter plug in the return fitting. This keeps water and ice out of the openings. Some setups also call for a gizmo-style plug in the skimmer bottom.
9. Add an air pillow and the cover. Inflate the pillow most of the way, not drum tight, and center it with ties. Put the cover on, then tighten the cable and winch so it sits snugly around the wall. Some owners add cover clips or a wrap to help in windy areas.

Read nextHow to Close an In-Ground Pool for Winter

What you’ll want on hand

Common closing mistakes

My sister and I made a few of these the first time. Some of them we learned from her neighbors.

• Closing in warm weather. Algae keeps growing under the cover, and spring opening turns into a cleanup job.
• Leaving water in the skimmer. That is exactly how her skimmer housing split. Lower the water or use a skimmer plate.
• Draining the pool all the way. A vinyl liner can shrink, wrinkle or pull loose. Most above-ground pools should keep plenty of water in winter.
• Over-inflating the air pillow. A drum-tight pillow can pop when ice presses on it. Most of the way full is enough.
• Leaving the pump outside. Even drained, many pumps and filters last longer stored out of the weather. Check your manual.
• Forgetting the cover after storms. Water and snow on top can stretch or tear the cover. Pump it off when it builds up.

Notes for salt systems, cartridges and sand

Different equipment needs a slightly different closing. These are the notes my sister keeps taped inside her shed door.

• Salt chlorine generator. Turn it off and unplug it before closing. Remove the cell if the manual says to, rinse it, and store it indoors. Do not leave it running into freezing weather.
• Cartridge filter. Hose the cartridge clean and let it dry fully before storing. A damp cartridge stored in a sealed bag can grow mildew. Some owners soak it in a cartridge cleaner first.
• Sand filter. Backwash, then set the valve to Winterize or the position your manual names. Remove the drain plug so the tank can empty.
• Hoses. Drain them, coil them loosely and store them out of the sun. Cold, brittle hoses can split when bent.
• Ladder and steps. Remove them, rinse them and store them flat if possible.

Write down where each part goes and take a few photos of the hose connections before you disconnect. In April, those photos save a lot of guessing.

Notes for mild and windy climates

In mild climates where freezes are short and rare, some owners keep the pump running on a shorter schedule all winter instead of fully closing. That can work, but a power outage during a cold snap can leave water sitting in the equipment. Talk to a local pool store about what is normal in your area.

In windy areas, a cover wrap or a set of cover clips can stop the wind from getting under the edge. My sister’s backyard gets gusts that come down off the foothills. Since she added a wrap, the cover has stayed put every winter.

During the winter

Closing is not quite set-and-forget. A few quick checks keep spring easier:

• Look at the cover after storms and remove standing water with a cover pump.
• Brush heavy snow off gently, without stepping near the pool.
• Check that the cable and winch are still snug.
• During a long warm spell, some owners lift a corner and add chlorine or algaecide, following the label.

When to call a pool pro

• You notice a leak, a bowed wall, rust on the wall panels or a damaged top rail.
• The liner has pulled loose, has a tear or shows heavy wrinkles.
• Your pool has a heater, salt system or hard plumbing that you are not sure how to drain.
• You suspect the pump motor or wiring has a problem. Electrical work is a job for a licensed pro.
• A hard freeze is coming and you cannot finish in time. Many pool services offer closing visits.