How to Winterize an Above Ground Pool Step-by-Step

Winterizing an above ground pool involves six steps: clean the pool, balance the water, add closing chemicals in the right sequence, lower the water to the correct level, protect the pump, filter, and plumbing, and secure the winter cover. Done in the right order, these steps help prevent freeze damage and make spring opening easier.

This guide focuses on seasonal closing for pools in cold-weather or freeze-prone regions, with notes for milder climates. Chemical dosages and equipment procedures should always follow the product label and your pool or equipment manufacturer’s guidance where those instructions differ from general recommendations.

A Quick Above Ground Pool Winterizing Checklist

The Day Before Closing

• Vacuum the pool or run the robotic cleaner one last time.

• Brush the walls and skim the surface.

• Test the water and adjust it to the proper closing range.

• Run the pump long enough to fully circulate any water-balance changes.

On Winterizing Day

• Add closing shock based on the product label and pool volume.

• Add winter algaecide later if the label says not to add it with shock.

• Lower the water to the correct level for your cover type.

• Backwash or clean the filter.

• Drain the pump and filter housing completely.

• Remove drain plugs, the skimmer basket, ladder, and other removable accessories.

• Blow out or protect the plumbing lines.

• Install the winter cover and secure it with the cable and winch.

After the Cover Goes On

• Check the cover after the first heavy rain, snow, or wind event.

• Tighten the cover if it has loosened.

• Inspect it through winter for standing water, tears, or sagging.

• Remove standing water from a solid cover.

• If you use an air pillow, make sure it stays inflated and centered.

When to Close an Above Ground Pool for Winter

Close the pool when the water temperature stays consistently below 60°F. Closing too early often leads to algae or cloudy water at spring opening because the closing chemicals are used up while the water is still warm. Closing too late creates a different risk: water may already have frozen inside the pump, filter, or plumbing before you drain and protect them.

Regional Timing by Climate

Northern states such as Minnesota, Wisconsin, Michigan, and New York usually close above ground pools between mid-September and early October, before repeated hard freezes make winterizing harder.

In much of the Mid-Atlantic and Midwest, including Pennsylvania, Ohio, Indiana, and Missouri, most owners close the pool in late October. Because the season stays mild longer, it is easier to delay closing for too long.

In milder parts of Texas, Florida, and Georgia, some owners do not fully close the pool every year. Instead, they reduce pump run time, lower chemical use, and keep the pool covered. But if freezing weather is expected, the pool still needs freeze protection.

Decide Whether Your Pool Needs Full Winterization

If freezing weather is possible, fully winterize the pool. In mild climates, some pools can stay in reduced winter operation, but hard-freeze events still require protection.

What You Need to Winterize an Above Ground Pool

Chemicals

Most above ground pools need:

• Pool shock to oxidize contaminants before closing

• Winter algaecide to help prevent algae under the cover

• pH and alkalinity adjusters to balance the water before closing

• Winter enzyme treatment if needed to break down oils and organic residue

• Phosphate remover for pools with recurring algae problems

Dose all chemicals by the product label, pool volume, and current water condition.

Related Reading: what pool chemicals do i need

Equipment

You may also need:

• A submersible pump or shop vac to lower the water

• An air compressor or Gizzmo-style plug to protect the skimmer and lines

• Pool-grade antifreeze for lines that cannot be fully cleared

• Basic tools to remove plugs, hoses, baskets, and accessories

The goal is simple: remove or protect any trapped water before it can freeze. Do not use automotive antifreeze.

Choose the Right Winter Cover

Solid cover: A solid cover blocks light and debris better, which usually makes spring opening easier. It also holds rainwater and snow on top, so it needs regular water removal.

Mesh cover: A mesh cover lets water pass through while blocking most large debris. It is easier to manage through winter, but the pool usually needs more cleanup in spring.

Safety cover: A safety cover is different from a standard winter cover. A standard solid or mesh cover is enough for most above ground pools, but it should not be treated as a safety cover. If children or pets can reach the pool area, use a locked gate or another barrier.

How to Winterize an Above Ground Pool Step by Step

Step 1: Clean the Pool Before Closing

Vacuum the floor, brush the walls, and skim the surface before adding any chemicals. Debris uses up chlorine, weakens the shock treatment, and often leads to algae or stains at spring opening.

If you use a robotic pool cleaner, run one last cycle before lowering the water. It can help remove fine sediment from the floor. Once the water level starts dropping, take the cleaner out, clean it, dry it, and store it indoors. Do not leave a robotic cleaner in the pool over winter.

Related Reading: Above-ground cleaning

Step 2: Balance the Water

Balance the water before adding closing chemicals. Water that goes under the cover out of range will stay that way all winter. Low pH can damage liners, fittings, and metal parts. High pH reduces chlorine efficiency.

Bring the water into the recommended closing range for your pool type. In most cases, that means checking pH, total alkalinity, sanitizer level, and any manufacturer-specific water requirements. General closing targets often put pH at 7.2 to 7.6 and total alkalinity at 80 to 120 ppm. Calcium hardness varies more by pool type and local water conditions, but vinyl liner pools should not stay at the very low end for long. If your pool or water-care system gives different targets, follow those instead.

After adjusting the water, circulate it fully and retest before moving on.

Step 3: Shock the Pool and Add Winter Chemicals

Add shock first, usually in the evening to reduce UV loss. Let it circulate fully through the pool.

If the algaecide label says to wait after shocking, follow that timing. Do not add both at once if the label says otherwise, since the shock can weaken the algaecide on contact.

After the shock has circulated and the label timing has passed, add winter algaecide based on pool volume. If your pool has recurring algae problems tied to phosphates, add phosphate remover before the algaecide. A winter enzyme treatment can also help reduce oils and organic residue over the off-season and make spring cleanup easier.

Step 4: Lower the Water to the Right Level

How far you lower the water depends on the cover.

With a solid cover, lower the water to about 4 to 6 inches below the bottom of the skimmer opening. With a mesh cover, lower it farther, usually 12 to 18 inches below the skimmer, because rain and snowmelt pass through the cover and raise the water level over winter.

Do not drain a vinyl liner pool completely. The liner needs the weight and pressure of the water to stay in place, and draining too low can cause shrinking, shifting, and long-term damage. If your above ground pool has a fiberglass shell, follow the manufacturer’s minimum water-level guidance, especially in wet areas where groundwater pressure may be a factor.

Step 5: Drain and Protect the Pump, Filter, and Plumbing

In freezing conditions, trapped water inside the pump, filter, or plumbing can freeze, expand, and crack the equipment. You may not notice the damage until spring startup, when the system is reassembled and starts leaking.

For sand filters, backwash first. Then set the multiport valve to the winterize setting, or to the non-operating position recommended by the manufacturer. Open the drain plug and let the tank drain fully. Leave the plug out for the winter and store it somewhere easy to find. On many residential systems, it also makes sense to remove the multiport valve handle and store it indoors.

For cartridge filters, turn off the pump, release the pressure, remove the cartridge, rinse it well, and let it dry completely before storing it indoors. A damp cartridge stored through winter is more likely to grow mold and wear out early.

For plumbing lines, blow them out with an air compressor or a compatible vacuum setup, working from the skimmer toward the returns. Once the lines are clear, plug them with the proper fittings. If a line cannot be fully cleared, add pool-grade antifreeze as directed on the product label. Remove the pump, hoses, skimmer basket, ladder, and other detachable accessories, and store them in a dry place protected from freeze-thaw exposure.

Step 6: Install and Secure the Winter Cover

Lay the cover over the pool and thread the cable through the perimeter grommets. Tighten it with the winch until the cover sits snugly against the pool wall without loose areas that can sag and collect water.

Many above ground pool owners use an air pillow under the cover, especially in snowy areas. It helps reduce stress on the cover and pushes water and snowmelt toward the edges instead of letting it collect in the center. Even with an air pillow, a solid cover still needs standing water removed in wet climates.

A tarp may work for a short-term emergency in mild weather, but it is not a reliable winter cover for a full season in a cold or snowy climate. It is not fitted to the pool, does not use a proper cable-and-winch system, and is more likely to sag or tear under rain or snow.

A standard winter cover is not a safety cover. It will not support the weight of a child or pet. If the pool area is accessible during winter, use a fence, gate, or enclosure for safety.

Step 7: One Final Check Before the Hard Freeze

Walk through the pool area and confirm that every drain plug has been removed and stored, every piece of equipment is out of the water, the cover cable is tight, and there is no standing water in any hose or fitting. A five-minute walkthrough before the first hard freeze prevents the most expensive winterizing mistakes.

How Much Water Should You Drain From an Above Ground Pool for Winter?

Lower the water 4 to 6 inches below the skimmer for a solid cover, and 12 to 18 inches below the skimmer for a mesh cover.

A solid cover keeps water out, so the pool level stays fairly stable. A mesh cover lets rain and snowmelt in, so the water level rises over winter. That is why mesh covers need more clearance below the skimmer.

Why Draining Too Much Is a Problem

Do not fully drain a vinyl liner pool. Without enough water pressure, the liner can shrink, shift, and pull away from the walls and fittings. The damage often shows up in spring when the pool is refilled and starts leaking.

Can You Winterize Without Draining the Pool?

Yes. Most winterizing steps are done with the pool still full. You only lower the water enough to protect the skimmer and match the cover type.

How to Winterize an Above Ground Pool with a Sand Filter or Cartridge Filter

The cleaning and water chemistry steps stay the same. The difference is how you drain and store the filter system.

Sand Filter

A sand filter holds a lot of water, so it must be drained fully before freezing weather.

• Backwash the filter first.

• Set the multiport valve to winterize, or to closed or recirculate if your model does not have a winterize setting.

• Open the drain plug at the bottom of the tank and let it drain completely. On some models, this can take 20 to 30 minutes.

• Leave the drain plug out and store it where you can find it in spring.

• Remove the multiport valve handle and store it indoors. Leaving it outside can lead to cracking from UV exposure and freeze-thaw cycles over time.

• Disconnect the pump, remove its drain plugs, and drain the pump housing fully. Store the pump indoors.

• If the system uses rigid PVC, blow out the lines.

• If it uses flexible hose, disconnect the hose, drain it, and store it coiled in a dry place.

Cartridge Filter

A cartridge filter is easier to winterize because there is no backwashing step and less water stays in the tank.

• Turn off the pump.

• Open the air bleed valve to release pressure.

• Remove the housing lid and take out the cartridge.

• Rinse the cartridge thoroughly with a garden hose.

• Check it for tears or crushed pleats. If it is near the end of its life, replace it now instead of waiting until spring.

• Let the cartridge dry fully, then store it indoors in a cool, dry place.

• Drain the filter housing completely.

• Remove all drain plugs.

• Store the pump and filter housing indoors.

• Blow out the plumbing lines the same way you would for a sand filter system.

Common Above Ground Pool Winterizing Mistakes to Avoid

• Closing too early: Warm water keeps algae active, so the closing chemicals do not last the way they should.

• Skipping water balance before shock: Poor chemistry weakens the whole treatment and stays trapped under the cover.

• Leaving water in the pump: Frozen water can crack the housing and turn into a leak at spring startup.

• Draining too much water: The liner can shift, shrink, or deform over winter.

• Leaving the ladder in place: It can cause corrosion, staining, or liner wear.

• Using a tarp for the full season: It usually cannot handle long-term rain, snow, and wind load.

• Not managing the cover: Standing water and poor support make sagging, tearing, and wind damage more likely.

Above Ground Pool Winterizing FAQ

Can You Use a Tarp to Cover a Pool in Winter?

A tarp can work as a temporary solution for a short closure in mild conditions, but it is not a true replacement for a winter pool cover in a full cold season. It is not fitted to the pool, does not use a proper cable system, and handles standing water and snow poorly.

Does an Above Ground Pool Need a Winterizing Kit?

A winterizing kit can be convenient, but the important thing is not the packaging. What matters is that the kit includes the right type of shock, a true winter algaecide, and the correct dosage range for your pool volume. If those parts are correct, a kit can work well.

How Long Should the Pool Pump Run Before Closing?

Run the system long enough to fully circulate each chemical addition through the pool, based on pool size, pump output, and product directions. The goal is complete circulation, not a rigid one-size-fits-all number.

What If the Pool Already Froze Before You Could Winterize It?

Do not force frozen equipment to run. Let the pump and lines thaw safely, inspect the system for cracks or damage, and then complete the winterizing process as soon as possible. If any line may still retain water afterward, protect it before the next freeze event.

How Often Should You Check the Pool Cover in Winter?

Check the cover after major storms and periodically through the winter. Look for standing water, tears, sagging areas, and loosening cable tension. Catching those issues early prevents more serious cover problems later in the season.

How Do You Prevent the Winter Cover From Sagging, Tearing, or Blowing Off?

A correctly fitted cover, strong cable tension, and regular top-water management do most of the work. In snow-prone regions, many pool owners also use an air pillow to help distribute stress and reduce deep pooling in the center.

How Do You Reduce Safety Risks From the Winter Cover?

Treat the pool area as a hazard even when the cover is on. Standard winter covers are not safety covers. If children or pets could access the area, a locked fence, gate, or enclosure is the right protection.

Can a Pool Cleaning Robot Stay in the Pool Through Winter?

No. Robotic pool cleaners should be removed before winterizing, cleaned, dried, and stored indoors. Leaving one in the pool through freezing temperatures can damage the motor, tracks, and electronics.

Final Thougnt

A little pool care before winter is what keeps an above ground pool cleaner, safer, and easier to reopen when the weather warms up again.

That is why the final cleanup matters. You can use a robotic pool cleaner, it can help remove the last layer of debris before closing and cut down on cleanup when you reopen the pool in spring.