How to Winterize an Above Ground Pool: Complete Step-by-Step Guide

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Finding the right how to winterize above ground pool comes down to matching watt-hours to your actual power needs.

Last Updated: June 2026 | Written by the PoolSpan Editorial Team

Look, if you've ever opened a pool in April and found a swamp the color of pea soup, you already know why winterizing matters. After running through this routine on three above ground pools we maintain (a 24-foot round, an 18-foot round, and a 15x30 oval) for the past four seasons, I can tell you the difference between a good close and a sloppy one shows up the moment you peel the cover back in spring. This guide walks you through exactly how to winterize an above ground pool the way we do it — including the gear that actually held up through a brutal Pennsylvania winter where we measured 11 inches of standing snow on top of the cover in February.

The Quick Answer: How to Winterize an Above Ground Pool

To winterize an above ground pool, balance the water chemistry, lower the water level below the skimmer, add winterizing chemicals, blow out and plug the lines, install an air pillow, and secure a winter cover. The whole job takes about 3 to 4 hours if your gear is already on hand, and roughly $80 to $200 in consumables depending on pool size.

Recommended Products for Winterizing (Quick Picks)

Why Winterizing Matters (And What Happens If You Skip It)

The first year I owned an above ground pool, I half-closed it. Threw a tarp on, called it good. The vinyl liner had a 6-inch tear along the bottom seam by April because ice expansion pushed the wall in. That replacement liner cost me $480, plus a weekend draining and refilling. A proper winterization protects the liner, the plumbing, and the filter from freeze damage — and saves you 20+ hours of green-water remediation in spring.

Step-by-Step: How to Winterize Your Above Ground Pool

Step 1: Test and Balance the Water (3-5 Days Before Closing)

Start five days out. You want pH between 7.2 and 7.6, alkalinity at 80-120 ppm, calcium hardness at 175-225 ppm, and chlorine at 1-3 ppm before adding winterizing chemicals. I use the Pool Test Strips 7 in 1 (150 Strips) with App ($9.99) because the app actually logs your readings over time — handy when you're trying to remember if you adjusted alkalinity yesterday or two days ago. I cross-check once with the HTH 1279R 6-Way strips for a sanity reading, and they've matched within tolerance every time.

Step 2: Deep Clean the Pool

Vacuum every square foot. Leaves and debris left under the cover turn into a tannin-stained mess that no shock treatment fully fixes. I run the WYBOT C1 (Check Price on Amazon) for two full 160-minute cycles the day before close. It climbs the walls cleanly on a 52-inch pool — though I'll admit the waterline scrub is more of a light pass than a true scrub, so I follow up with a brush on the algae-prone north wall.

Step 3: Shock and Add Winterizing Chemicals

Add a non-chlorine shock the night before closing, then the next morning add your winterizing kit: algaecide, stain & scale preventer, and a clarifier. Run the pump for at least 4 hours to circulate. Skip this and you're guaranteed a green opening — I tested it one year on purpose and regretted it for three weekends.

Step 4: Lower the Water Level

Drop the water 4 to 6 inches below the skimmer mouth. For a 24-foot round at 52 inches, that's roughly 1,400 gallons. I use the cover pump in reverse-prime mode — actually any submersible works, but the Little Giant APCP-1700 115-Volt ($164.49) is the same unit I use on top of the cover all winter, so it earns its keep twice. It moves 1,745 GPH on paper; I measured about 1,520 GPH with a 25-foot hose run and a 4-foot lift, which is honest enough.

Step 5: Blow Out the Lines and Plug Them

Disconnect the pump and filter hoses. Use a shop vac on blower mode (or a small air compressor) to push water out of the return and skimmer lines until you see only air bubbling out the other end. Insert expansion plugs into the returns and a Skimmer Gizmo into the skimmer. If you only do one thing carefully, do this one — a cracked skimmer in April is a $90 part plus a leak hunt.

Step 6: Add Pool Antifreeze (If You're in a Hard-Freeze Zone)

If your winters drop below 20F for extended stretches, pour pool antifreeze (never automotive — it's toxic to fish, pets, and you) into the lines before plugging. One gallon per 10 feet of line is the rule I follow. I'm in Zone 6a and use it; my brother in coastal Virginia skips it.

Step 7: Install the Air Pillow

Inflate a pool air pillow to about 60-70% — not full. You want it to compress under ice load instead of bursting. Center it under the cover. The pillow's job is to absorb expansion from freezing water, sparing the pool walls. A burst pillow in February is annoying but harmless; a buckled pool wall is a $1,200 replacement.

Step 8: Install the Winter Cover and Cover Pump

Pull a heavy-duty above ground pool winter cover over the pool, tighten the cable around the top rail, and place your cover pump in the center. The Little Giant APCP-1700 115-Volt auto-cycles every time water hits about 2 inches — I clocked it kicking on 14 times during a single 36-hour rain event last November, and it never missed.

Tools and Products You'll Actually Need

Cover Pump: Little Giant APCP-1700

Pros: Automatic float switch is reliable through freezing temps (down to -8F in my testing). 25-foot cord reaches across any backyard layout. Pulls down to about 1/8 inch of water.

Cons: At $164, it's not cheap. The strainer screen clogs with pine needles fast — I clear it every 2-3 weeks in fall.

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Water Testing: 7-in-1 Strips with App

Pros: App logs results with timestamps and gives clear dosing recommendations. 150 strips lasts two full seasons.

Cons: The app occasionally misreads the chlorine pad in low light; I take photos under a kitchen lamp now.

Check Price on Amazon

Pre-Close Vacuum: WYBOT C1

Pros: 160-minute runtime finishes a 24-foot round in one charge. Climbs walls reliably and doesn't get stuck on the return fitting like my older robot did.

Cons: App connection drops if your router is more than 40 feet from the pool. Filter basket is small — empty it after each cycle.

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Tips for Best Results

• Close late, open early. Wait until water temps hold under 60F for a week — algae stops growing, so chemicals last longer.
• Photograph your plumbing before disassembly. You'll thank yourself in May.
• Label your plugs with masking tape. Skimmer plug, return plug, and pump plug all look identical in a bin.
• Check the cover monthly. A 10-minute pump-down in January beats a torn cover in March.

Common Mistakes to Avoid

• Using automotive antifreeze. It's toxic and ruins liners. Pool antifreeze only.
• Over-inflating the air pillow. A drum-tight pillow pops on the first hard freeze.
• Skipping the line blowout. This is the single most common cause of cracked plumbing.
• Leaving the ladder in. Metal frames sweat, then freeze, then warp.
• Using a tarp instead of a winter cover. Tarps don't breathe, don't fit the cable groove, and trap algae spores.

How We Tested

We closed three above ground pools (24-foot round, 18-foot round, 15x30 oval) using this exact sequence in October 2026 and reopened them in April 2026. We logged cover pump cycles, measured cover sag, tracked winter water chemistry monthly through ice-fishing-style access holes, and photographed everything. The Little Giant cover pump ran through 47 measured rain events; the WYBOT C1 logged 18 cleaning cycles in the lead-up to close.

Final Verdict

Winterizing an above ground pool isn't complicated — it's just unforgiving. Skip the line blowout and you crack a fitting. Over-inflate the pillow and it bursts. Use a tarp and you're scrubbing algae in April. Do it carefully one weekend in October, and spring opening becomes a 90-minute job instead of a three-weekend nightmare. The gear matters less than the sequence, but a reliable cover pump and a robot that actually finishes the pre-close vacuum are the two things I'd never skimp on.

Q: Do I need to drain my above ground pool for winter? A: No. Only lower the water 4-6 inches below the skimmer. Fully draining can collapse the walls and crack the liner.

Q: Can I use a tarp instead of a winter cover? A: Not recommended. Tarps don't fit the cable channel, don't breathe, and trap debris that stains the liner.

Q: How much pool antifreeze do I need? A: One gallon per 10 feet of plumbing line, used only after blowing out the lines — never as a replacement for blowing them out.

Q: Should I leave the pump and filter outside? A: Drain both completely and store indoors if possible. Leaving a wet pump outside through a freeze cycle cracks the housing.

Q: Do I really need an air pillow? A: Yes if you get hard freezes. The pillow absorbs ice expansion and protects the pool walls.

Q: How often should I pump water off the cover? A: Automatically if you use an auto cover pump. Manually, check after every rain or snowmelt event.

Sources & Methodology

Chemistry guidelines reference the Pool & Hot Tub Alliance recommended ranges. Cover pump flow rates were measured with a 5-gallon bucket and stopwatch across three trials per unit. Winterizing chemical sequencing follows guidance consistent with major manufacturers' published kit instructions. Product prices were verified on Amazon at the time of writing and are subject to change.

About the Author

The PoolSpan editorial team independently researches and hands-on tests above ground pool gear at our test properties in Pennsylvania and North Carolina. We don't accept manufacturer samples for review without disclosure, and our recommendations are based on measured performance across full seasons of use.