Leaves & Debris
How to Winterize a Pool
The water in the pool is not what cracks in January. The water left in the lines is.
We have not handled these products and we do not pretend to have. Here is what we did instead. Links to Amazon earn us a commission at no extra cost to you, and commission never decides a pick — disclosure.
| # | Product | Best for | The spec it turns on | Price |
|---|---|---|---|---|
| 1 |  Vizava Rubber Pool Winter Plugs, 4-pack with T-HandleTop pickFour sizes in one bag, which is the right purchase when you have not measured your returns and the pool store is closed on Sunday. | Not knowing your fitting sizes yet | Listing states four sizes - 1 in, 1.25 in, 1.5 in and 2 in - with stainless steel wing nuts and a T-handle, and publishes each plug's dimensions | |
| 2 |  Champion Pool Antifreeze, 1 Gallon, CH201402The one bottle worth buying at closing, and only for the plumbing. It states a freeze figure, states it is non-toxic, and states not to dilute it. | Protecting the lines you cannot fully clear | Listing states protection to -50 degrees F, non-toxic, ready to use and not to be diluted | |
| 3 |  Gizzmo Gizzmo 4102 Skimmer Freeze Protection, 16 inThe part that stops the most expensive winter repair there is. A cracked skimmer housing means breaking concrete to replace it. | Deep in-ground skimmers | Listing states a 16 in unit that threads into 1.5 in or 2 in skimmer threads (MPT) to prevent freeze damage | |
| 4 |  Swimline Stainless Steel Pool Winterizing Plate, 89403The above-ground answer to the same problem: seal the skimmer off so the pool can hold water above it and ice never gets in. | Above-ground through-wall skimmers | Listing states an OEM replacement plate for standard through-wall skimmers, stainless steel, part 89403 | |
| 5 |  Swimline Above-Ground Pool Winter Cover Air Pillow, 4 x 8 ftTwice the footprint of a 4 x 4 for about the same money, which is the right shape for a bigger pool even though the listing states no gauge. | Larger round pools | 4 x 8 ft cushion with a large valve opening; described by the maker as an ice compensator | |
| 6 |  MCSAPIL Pool Cover Clips for Above-Ground Pools, 60-packThe cheapest thing on this page and the one that saves the cover. Wind under an unclipped cover is what tears grommets out. | Stopping an above-ground cover blowing off | Listing states 60 clips at 4.7 x 1.2 x 0.63 in, for most permanent above-ground pools | |
| 7 |  Splash Pool & Spa Antifreeze -50F, 2 x 1 GallonTwo gallons, and the only listing here that names the materials it is safe against. If your plumbing includes metal fittings, that sentence is the reason to buy this one. | Longer runs, and equipment you want named | Listing states burst protection to -50 degrees F and compatibility with brass, copper, galvanized steel and most plastics except acetate | |
| 8 |  Air Supply 3 HP Cyclone Pool Line Blower and Vinyl Liner Vacuum, 4128100PThe proper tool, at a price that only makes sense if you are closing your own pool for years rather than hiring it out once. | Owners who close their own pool every year | Listing states a 3 HP 120 V motor, 2 in NPT intake with a 1.5 in hose adapter discharge, 4 in vacuum inlet and a 6 ft cord |
What you are actually protecting
A frozen pool full of water is mostly fine. Ice forms on the surface, the water below stays liquid, and a covered pool comes through a hard winter without harm. What does not come through is water sitting in a pipe with nowhere to expand.
Water expands when it freezes, and a sealed line has no give in it. The failures are always the same: a cracked skimmer housing, a split return line under the deck, a pump volute broken across the face, a heater exchanger destroyed. The pool survives; the plumbing does not.
That is the whole logic of a close. Everything below is about getting water out of places it cannot escape from, and keeping it out until spring.
In-ground and above-ground close differently
The two jobs share a sequence and differ on the three steps that matter most, so it is worth knowing which page you are reading before you buy anything.
| In-ground | Above-ground | |
|---|---|---|
| Water level | Below the skimmer, or per your cover's instructions | Above the skimmer, with the skimmer sealed off |
| The skimmer | Gizzmo threaded into the suction port | Winterizing plate bolted over the throat |
| Lines | Blown clear, plugged, antifreeze in what is left | Short runs, usually disconnected and drained |
| The cover | Solid cover with a pump, or an anchored mesh safety cover | Solid cover, clips, and an air pillow under it |
| Equipment | Pump, filter, heater drained and often removed | Pump and filter drained, usually stored indoors |
The water level line is the one people get backwards. An in-ground pool drops below the skimmer so the skimmer cannot fill; an above-ground pool stays high and seals the skimmer instead, because dropping the level far enough on a soft-sided pool risks the wall.
The sequence
- Balance and shock, with the pump running long enough to circulate it. The full sequence and dose arithmetic are on pool closing chemicals.
- Clean the pool properly - brush, vacuum, empty the baskets. Organic debris left under a cover is what feeds a spring bloom.
- Lower the water to the level your cover calls for. Below the skimmer mouth in-ground; above it on an above-ground pool with the skimmer plated.
- Drain the equipment. Pump, filter, heater and chlorinator all have drain plugs, and every one of them has to come out and stay out until spring.
- Blow the lines clear from the equipment pad, one at a time, until air bubbles out of the pool fitting.
- Plug each return as the air is still blowing, so the line stays empty rather than drawing water back.
- Protect the skimmer - gizzmo in-ground, winterizing plate above-ground.
- Add pool antifreeze to any line you could not clear confidently, especially a main drain run or a line with a rise in it.
- Fit the air pillow if the pool is above-ground, then the cover, then the clips or the cable.
- Store the drain plugs in the pump basket, not in a drawer. You will look for them in April and the basket is where you will look.
Blowing the lines is the step that matters
Everything else on this page is insurance on this step. A line that is genuinely empty cannot freeze, whatever the weather does.
A shop vacuum switched to blow clears a short run on a small pool. It runs out of pressure on a long line, a main drain, or any run that climbs - and those are exactly the lines that crack. A purpose-made blower is the tool for that: the Air Supply Cyclone states a 3 HP 120 V motor with a 2 in NPT intake and a 1.5 in hose adapter, which is what lets it couple to pool plumbing instead of being taped to it.
Work one line at a time from the pad, and watch the fitting in the pool. When air is bubbling steadily out of the return, that line is clear - plug it while the air is still blowing, not after.
What antifreeze actually does
Pool antifreeze protects the water you could not get out. It is not a method on its own, and it does not go in the pool - it goes in the lines.
Champion states protection to -50 degrees F, that it is non-toxic and safe in all types of pool plumbing, and - importantly - that it is ready to use and should not be diluted. Splash states burst protection to the same -50 degrees F and goes further on materials, naming brass, copper, galvanized steel and most plastics as compatible, with acetate excluded.
Automotive antifreeze is not a substitute at any price. These products are labeled non-toxic for pool plumbing; the stuff in your car is not sold for this, is not labeled for it, and ends up in the pool at opening.
The skimmer is where pools crack
A skimmer is a plastic box set into the wall with a pipe out of the bottom. Fill it with water, freeze it, and the ice has nowhere to go but outward through the housing - and replacing an in-ground skimmer means breaking out the deck around it.
In-ground pools solve it with a gizzmo: a hollow tube that threads into the skimmer's suction port and stands up inside the throat. Ice crushes the tube instead of the box. The Gizzmo 4102 states a 16 in length for deep skimmers and fits 1.5 in or 2 in MPT threads - measure your skimmer depth first, because a gizzmo that does not reach the water is decoration.
Above-ground pools solve it differently, because the water stays above the skimmer. A winterizing plate bolts over the throat using the faceplate screws and seals the opening, so the pool can hold its level and the skimmer stays dry. Swimline's states stainless steel and an OEM part number, and it is for standard through-wall skimmers - wide-mouth skimmers take a different plate.
Plugs: the small parts that decide the job
A return plug is a rubber cylinder squeezed between two washers by a wing nut. Tighten it and the rubber bulges into the fitting and seals. Under-tighten it and water creeps back down the line; over-tighten it and the rubber splits.
Buy the sizes your pool uses, or buy a set if you have not measured. The Vizava set covers 1 in, 1.25 in, 1.5 in and 2 in, publishes the actual rubber dimensions for each, and uses stainless wing nuts - which matter, because a plated nut seizes over a winter and fights you at opening.
Treat plugs as a consumable. Rubber perishes, and a plug that sealed for three winters is the one that lets go in the fourth.
Above-ground extras: the pillow and the clips
An air pillow is not padding for the cover. It sits under the cover in the middle of the pool, and its job is to take the compression when the surface freezes - ice pushes in toward the pillow rather than out against the wall.
It also domes the cover so rain and snowmelt run to the edges instead of pooling in the middle, which is the other way covers fail. Inflate it to about three quarters, not hard: a fully inflated pillow splits when the ice squeezes it, which is the moment it was bought for.
Cover clips do the rest. Wind that gets under an unclipped cover tears the grommets out and, on a bad night, puts the whole cover in the trees. Sixty clips is enough to run a full perimeter with no gaps - the MCSAPIL set publishes its clip dimensions, which is worth checking against your top rail, because rail profiles vary by maker. Cover choice itself is on best winter pool cover.
The picks
Top pick - Not knowing your fitting sizes yet
Vizava Rubber Pool Winter Plugs, 4-pack with T-Handle
Four sizes in one bag, which is the right purchase when you have not measured your returns and the pool store is closed on Sunday.
The published figure
Listing states four sizes - 1 in, 1.25 in, 1.5 in and 2 in - with stainless steel wing nuts and a T-handle, and publishes each plug's dimensions
The listing covers 1 in, 1.25 in, 1.5 in and 2 in plugs, and it publishes the actual rubber dimensions for each - top and bottom diameter and height - which is rare and lets you check against your fittings before ordering.
Stainless steel wing nuts matter more than they sound. A plated nut seizes or rusts over a winter and the plug fights you at opening.
The T-handle is for tightening without a wrench. An expansion plug works by squeezing the rubber until it seals, and an under-tightened plug is the one that lets water back into the line.
What it does well
- Four common sizes in one purchase
- Publishes the dimensions of each plug
- Stainless wing nuts and a T-handle included
What it costs you
- Rubber expansion plugs are a consumable - they perish over a few seasons
- No size covers a 2.5 in fitting
- Over-tightening splits the rubber, and there is no torque guidance
Skip it if you already know your sizes. Buying the one size you need costs less and leaves nothing spare in a drawer.
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Pick 2 - Protecting the lines you cannot fully clear
Champion Pool Antifreeze, 1 Gallon, CH201402
The one bottle worth buying at closing, and only for the plumbing. It states a freeze figure, states it is non-toxic, and states not to dilute it.
The published figure
Listing states protection to -50 degrees F, non-toxic, ready to use and not to be diluted
Champion states protection down to -50 degrees F and that the product is non-toxic and safe in all types of pool plumbing. Both matter: this goes into lines that will hold water against your equipment all winter.
It is stated as ready to use - do not dilute. Watering it down is the common mistake, and it turns a -50 rating into an unknown one.
The listing also states protection from rust and metal corrosion, which is the secondary job: standing water in a line does more than freeze.
What it does well
- States a -50 degrees F freeze rating
- Stated non-toxic and safe for pool plumbing
- Ready to use, with an explicit do-not-dilute instruction
What it costs you
- One gallon does not go far on a long or multi-line run
- Not a substitute for blowing the lines out
- Third-party seller, so delivery time varies
Skip it if your lines were blown clear and plugged properly. Antifreeze is insurance on what is left behind, not a method on its own.
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Pick 3 - Deep in-ground skimmers
Gizzmo Gizzmo 4102 Skimmer Freeze Protection, 16 in
The part that stops the most expensive winter repair there is. A cracked skimmer housing means breaking concrete to replace it.
The published figure
Listing states a 16 in unit that threads into 1.5 in or 2 in skimmer threads (MPT) to prevent freeze damage
A gizzmo threads into the skimmer's suction port and stands up inside the throat. Ice that forms in the skimmer crushes the hollow tube instead of the housing, which is the whole idea.
This one is stated at 16 inches for big, deep skimmers, and states it fits 1.5 in or 2 in MPT threads. Measure your skimmer depth before choosing a length - a gizzmo that does not reach the water does nothing.
The listing is thin beyond that, with no material or wall-thickness figure published.
What it does well
- Threads into standard 1.5 in or 2 in skimmer ports
- 16 in length suits deep in-ground skimmers
- Sold and shipped by Amazon
What it costs you
- Very little published beyond length and thread size
- Wrong length is a common and useless purchase
- Single-season item on some pools - they do crack, which is their job
Skip it if your pool is above-ground with a through-wall skimmer. That takes a winter plate, not a gizzmo.
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Pick 4 - Above-ground through-wall skimmers
Swimline Stainless Steel Pool Winterizing Plate, 89403
The above-ground answer to the same problem: seal the skimmer off so the pool can hold water above it and ice never gets in.
The published figure
Listing states an OEM replacement plate for standard through-wall skimmers, stainless steel, part 89403
An above-ground pool closes with the water level above the skimmer, which means the skimmer opening has to be blocked. A winterizing plate bolts over the throat with the existing faceplate screws.
Swimline states stainless steel and an OEM replacement part, 89403, for standard through-wall skimmers. Stainless is the right call on a part that sits half-submerged for five months.
It is stated for standard skimmers - wide-mouth skimmers take a different plate, and the two are not interchangeable.
What it does well
- Stainless, so it does not rust into the faceplate
- OEM part number published
- Sold and shipped by Amazon
What it costs you
- Standard through-wall skimmers only, not wide-mouth
- Gasket is not stated as included
- Useless on an in-ground skimmer
Skip it if your skimmer is wide-mouth. Match the plate to the skimmer or it will not seal.
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Pick 5 - Larger round pools
Swimline Above-Ground Pool Winter Cover Air Pillow, 4 x 8 ft
Twice the footprint of a 4 x 4 for about the same money, which is the right shape for a bigger pool even though the listing states no gauge.
The published figure
4 x 8 ft cushion with a large valve opening; described by the maker as an ice compensator
Swimline calls these ice compensators, which is the clearest description of the job in this category: they absorb the pressure of freezing and expanding water so that the pool wall and the cover do not.
4 x 8 ft is the size that suits a larger round above-ground pool, where a small pillow leaves too much of the surface free to freeze flat against the cover.
The listing states puncture-resistant heavy-duty material but no gauge, so it cannot be compared with the Blue Wave pillow on construction. The large valve is a genuine convenience when you are inflating it in October.
What it does well
- 4 x 8 ft suits larger round pools
- Large valve opening makes inflating and deflating quick
- Deflates flat for storage
What it costs you
- No vinyl gauge stated, so construction cannot be compared
- No warranty or expected life stated
- Still needs rope to tie it in place
Skip it if you want a published construction figure. Blue Wave states 16-gauge vinyl and this listing states none.
Pick 6 - Stopping an above-ground cover blowing off
MCSAPIL Pool Cover Clips for Above-Ground Pools, 60-pack
The cheapest thing on this page and the one that saves the cover. Wind under an unclipped cover is what tears grommets out.
The published figure
Listing states 60 clips at 4.7 x 1.2 x 0.63 in, for most permanent above-ground pools
The listing publishes the clip dimensions - 4.7 in long, 1.2 in wide, 0.63 in high - and states they suit most permanent above-ground pool walls. Measure your top rail before ordering, because rail profiles vary.
Sixty clips is enough to run the whole perimeter without gaps, which is the point: one unclipped span is where the wind gets underneath.
They are plastic, not metal, which the listing frames as a feature - it means they never rust into the rail. It also means UV eventually makes them brittle.
What it does well
- Publishes clip dimensions
- Enough clips to do a whole pool with no gaps
- Plastic, so nothing rusts onto the rail
What it costs you
- Plastic clips become brittle after a few seasons of UV
- Fit depends on your top rail profile, which varies by maker
- No use on an in-ground pool
Skip it if your cover is a tensioned in-ground safety cover. Those anchor into the deck and need no clips.
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Pick 7 - Longer runs, and equipment you want named
Splash Pool & Spa Antifreeze -50F, 2 x 1 Gallon
Two gallons, and the only listing here that names the materials it is safe against. If your plumbing includes metal fittings, that sentence is the reason to buy this one.
The published figure
Listing states burst protection to -50 degrees F and compatibility with brass, copper, galvanized steel and most plastics except acetate
Splash states burst protection down to -50 degrees F and lists what it is compatible with: brass, copper, galvanized steel and most plastics, with acetate called out as the exception.
It states the formula contains ethanol, which is unusual candor for this category - most antifreeze listings name no active ingredient at all.
Two gallons covers a pool with several return lines, a spa spillover or a long run to a remote pad, where a single gallon runs out halfway.
What it does well
- Names the materials it is compatible with
- States burst protection to -50 degrees F
- Two gallons for multi-line plumbing
What it costs you
- Acetate plastics are explicitly excluded
- Twice the volume than a small single-skimmer pool needs
- Third-party seller, so delivery time varies
Skip it if you have one skimmer and one return. A single gallon is the honest size for that pool.
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Pick 8 - Owners who close their own pool every year
Air Supply 3 HP Cyclone Pool Line Blower and Vinyl Liner Vacuum, 4128100P
The proper tool, at a price that only makes sense if you are closing your own pool for years rather than hiring it out once.
The published figure
Listing states a 3 HP 120 V motor, 2 in NPT intake with a 1.5 in hose adapter discharge, 4 in vacuum inlet and a 6 ft cord
Air Supply states a 3 HP 120 V motor with a 2 in NPT intake and a 1.5 in hose adapter on the discharge, which is what lets it couple to pool plumbing rather than fight it.
It states dual use - winterizing lines and installing vinyl liners - and a 4 in vacuum inlet, which is the liner-fitting side of the job.
A shop vacuum on blow will clear a short run on a small pool. It will not reliably clear a long main drain line or a run with a rise in it, and that is the case this machine exists for.
What it does well
- Published motor rating and fitting sizes
- Couples to pool plumbing without adapters improvised on the day
- Doubles as a liner-fitting vacuum
What it costs you
- Costs many times the rest of this page combined
- 6 ft cord means an outdoor-rated extension lead on most pads
- Overkill for a small above-ground pool with two short lines
Skip it if you close once and hire a service the other years. Renting or borrowing beats owning at this price.
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Five mistakes that cost you a spring
- Closing too early. A pool closed while the water is still warm grows algae under the cover for weeks, because the sanitizer fades long before the water gets cold. Wait for a settled cold spell rather than a free weekend.
- Leaving a drain plug in. One plug still seated in the pump is enough to hold the water that cracks the housing.
- Skipping the skimmer. It is the single most expensive freeze repair and the cheapest one to prevent.
- Draining an in-ground pool for winter. Groundwater can float an empty shell out of the ground. Lower the level; never empty it.
- No cover pump on a solid cover. Water ponds, then freezes, and the weight pulls the cover in - best pool cover pump covers that job.
What we could not verify
How far a gallon of antifreeze protects in a partly cleared line - that depends on how much water is left, which nobody can publish. Gizzmo wall thickness and material, which the listing does not state. And the rail profiles those cover clips fit: the dimensions are published, the compatible pool models are not.
Questions people actually ask
How do you winterize a pool step by step?
How low should the water be to close a pool?
Do I need pool antifreeze if I blow the lines out?
Can I use car antifreeze in my pool lines?
What does a gizzmo do?
Should I inflate a pool air pillow fully?
When should I close my pool?
Sources
Every figure on this page traces to one of these. Where a number could not be sourced, the page says so rather than estimating.
- Skim & Soak methodology - the constants, formulas and worked examples behind every dose on this site
- Champion Pool Antifreeze, 1 gallon, -50 F, do not dilute - Amazon listing, read 2026-09-26
- Splash Pool & Spa Antifreeze -50 F, 2 x 1 gallon, material compatibility stated - Amazon listing, read 2026-09-26
- Vizava Rubber Pool Winter Plugs, 4-pack with T-handle, dimensions published - Amazon listing, read 2026-09-26
- Gizzmo 4102 Skimmer Freeze Protection, 16 in, 1.5 in or 2 in MPT - Amazon listing, read 2026-09-26
- Swimline Stainless Steel Pool Winterizing Plate, part 89403 - Amazon listing, read 2026-09-26
- Swimline Above Ground Pool Winter Cover Air Pillow, 4 x 8 ft - Amazon listing, read 2026-09-26
- MCSAPIL Pool Cover Clips, 60-pack, 4.7 in - Amazon listing, read 2026-09-26
- Air Supply 3 HP Cyclone Pool Line Blower, 4128100P - Amazon listing, read 2026-09-26
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