8 Essential Pool Closing Winterization Supplies for Your Backyard Pool

The autumn breeze brings colorful leaves, but for pool owners, it also signals the inevitable end of swim season. Shifting your focus from summer recreation to off-season protection is the single most important maintenance step of the year. Investing in the right winterization gear now prevents catastrophic freeze damage and ensures a crystal-clear opening next spring.

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Why Proper Winterization Saves Your Pool Budget

Leaving a pool vulnerable to freezing temperatures is an expensive gamble that rarely pays off. Water expands by nearly nine percent when it turns to ice, exerting immense pressure on PVC pipes, skimmer walls, and concrete shells. A single cracked underground pipe can cost thousands of dollars to locate and repair, turning your backyard oasis into a construction zone.

Beyond physical structure damage, poor winterization invites aggressive algae blooms that feast on stagnant water as soon as early spring temperatures rise. Cleaning up a swampy pool requires massive doses of expensive shock, algaecide, and endless hours of filtration. By spending a fraction of your budget on quality closing supplies, you protect your pool investment and ensure a stress-free spring opening.

Winterizing Kit – In The Swim Pool Winterizing Kit

A winterizing chemical kit is your first line of defense against off-season staining and biological growth. Instead of guessing chemical ratios, a pre-packaged kit provides a slow-release formula designed to survive freezing temperatures and low light. The In The Swim Pool Winterizing Kit delivers a balanced punch of winter shock, algaecide, stain preventer, and a time-release floater to keep water clear for months.

This kit stands out because of its convenience and reliability, using a non-chlorine shock that won’t bleach vinyl liners or damage plaster finishes. The included slow-dissolving winter floater continuously sanitizes the water without raising cyanuric acid levels.

• Kit Sizes: Available for pools up to 10,000, 20,000, and 35,000 gallons.
• Included Components: Winter shock, winter algaecide, metal-free stain preventer, and a patented winter floater.
• Compatible Pool Types: Safe for vinyl, plaster, fiberglass, and concrete pools.

This kit is perfect for owners who want a straightforward, reliable chemical regimen without multiple trips to the pool store. It is not ideal for pools with heavy active leaks, as water loss will dilute the chemicals before spring arrives.

Safety Cover – Loop-Loc Brass Anchor Safety Cover

A flimsy tarp held down by water bags is a recipe for disaster when heavy winter snows and high winds arrive. A tension-secure safety cover keeps leaves, limbs, and wildlife out of your pool while providing a critical safety barrier for children and pets. The Loop-Loc Brass Anchor Safety Cover is the industry gold standard, renowned for its legendary strength and flawless fit.

Crafted from ultra-strong, lightweight polypropylene mesh, this cover allows rain and melting snow to drain through while filtering out fine debris. The flush-mount brass anchors screw down flat into your pool deck during the summer, eliminating toe-stubbing hazards when the pool is open.

• Material: High-density, UV-stabilized polypropylene mesh.
• Anchoring System: Corrosion-resistant solid brass anchors.
• Safety Rating: Meets or exceeds ASTM F1346-91 safety standards.

This cover is an absolute must-have for families with young children or pets, and anyone living in areas prone to heavy snow loads. However, it requires a solid concrete, wood, or stone deck for proper anchor installation, making it unsuitable for soft-dirt or lawn surrounds without special stakes.

Pool Pillow – Swimline 4×15 Foot Air Pillow

Above-ground pools face a unique winter threat: freezing water expands outward, putting immense pressure on the pool walls and top rails. A pool pillow, or ice equalizer, floats in the center of the water to absorb this expansion pressure by collapsing inward under ice squeeze. The Swimline 4×15 Foot Air Pillow is built from heavy-gauge vinyl specifically to withstand this brutal compression.

By creating a central void in the ice sheet, this pillow forces the ice to expand inward toward the cushion rather than outward against your pool’s metal walls. Its elongated shape makes it easier to center and secure using the built-in grommets on each corner.

• Inflation Rule: Fill only to 60–80% capacity to allow room for compression.
• Material: Heavy-duty, freeze-resistant vinyl.
• Dimensions: 4 x 15 feet, ideal for oval and round above-ground pools.

This is an indispensable tool for above-ground pool owners in cold climates, preventing split walls and ruined liners. It is not necessary for in-ground pools unless you are using a solid cover and want to prevent water from pooling in the center.

Expansion Plug – Blue Devil Rubber Winter Plug

Once you blow the water out of your pool plumbing lines, you must seal them off hermetically to prevent water from creeping back in. Standard plastic threaded caps often crack under freezing temperatures, allowing water to re-enter and freeze inside the pipes. The Blue Devil Rubber Winter Plug uses a heavy-duty expansion design that creates an airtight, watertight seal inside the pipe.

This plug features high-grade, freeze-resistant rubber and a corrosion-resistant stainless steel wing nut that expands the rubber sleeve when tightened. This mechanical expansion ensures the plug remains locked in place even under backpressure from shifting ground water.

• Common Sizes: Available in #10 (1.5-inch) and #11 (2-inch) pipe sizes.
• Hardware: Heavy-duty, rust-proof stainless steel bolts and washers.
• Applications: Ideal for return lines, cleaner lines, and skimmer bottoms.

These plugs are a mandatory purchase for any pool owner winterizing an in-ground pool in a freezing climate. Be sure to measure your return line diameters carefully before ordering, as a loose plug will fail under freeze pressure.

Skimmer Guard – Ultra Gizzmo Winter Compensator

Your pool’s skimmer is especially vulnerable to winter damage because water naturally collects in its plastic throat and housing. If this water freezes, it expands outward, easily cracking the skimmer body and requiring an expensive deck-demolition repair. The Ultra Gizzmo Winter Compensator serves a dual purpose by sealing the plumbing line while absorbing ice expansion within the skimmer well.

This heavy-duty, hollow plastic tube collapses under the pressure of freezing ice, diverting the force away from the delicate skimmer walls. The Ultra Gizzmo features dual-thread options on the bottom, allowing it to screw directly into both 1.5-inch and 2-inch skimmer ports.

• Thread Sizes: Dual-threaded for 1.5-inch and 2-inch internal threads.
• Length: 16 inches, offering ample expansion protection.
• Bypass Tube: Integrated blowout channel for easy line clearing.

This is a crucial defense mechanism for all in-ground pool owners using standard skimmers. Make sure to wrap the threads with Teflon tape before installation to guarantee a water-tight seal at the base of the skimmer.

Pool Antifreeze – Splash RV & Marine Antifreeze

Even after blowing out your pool lines, gravity and condensation can cause water to collect in low spots underground. Utilizing a dedicated pool antifreeze provides a vital safety margin against localized freeze damage. Splash RV & Marine Antifreeze is a non-toxic propylene glycol formula designed to keep plumbing safe down to extreme temperatures.

Unlike automotive antifreeze, which is highly toxic and will ruin your pool’s chemistry, this formula is biodegradable and completely safe for pool plumbing, vinyl liners, and plaster surfaces. It will not damage your filtration system when you pump it out during spring startup.

• Base Ingredient: Non-toxic Propylene Glycol (safe for marine and pool use).
• Freeze Protection: Rated down to -50°F (-46°C).
• Compatibility: Safe for copper, PVC, and flexible plastic piping.

This antifreeze is highly recommended for cold-climate pool owners, particularly those with complex plumbing layouts containing deep underground loops. Never pour this directly into the pool heater or chlorinator, as it is strictly meant for the plumbing lines.

Cover Pump – Wayne WAPC250 Pool Cover Pump

Rainwater and melting snow quickly accumulate on top of solid winter covers, creating heavy pools of water that stress the cover springs and anchor points. Left unchecked, this stagnant water also becomes a safety hazard and a breeding ground for mosquitoes. The Wayne WAPC250 Pool Cover Pump automated system removes this water effortlessly before it can damage your cover.

This submersible pump features smart i-Switch technology that automatically turns the pump on when water is detected and shuts it off once the cover is dry. It can move up to 3,000 gallons per hour, clearing heavy water build-up rapidly while filtering out leaves and debris through its stable, wide base.

• Flow Rate: Up to 3,000 Gallons Per Hour (GPH).
• Switch Type: Automatic freeze-protection water sensor.
• Power Cord: 25-foot heavy-duty power cable.

This pump is a lifesaver for anyone using a solid pool cover or a dense mesh cover that accumulates standing water. It does require access to a dedicated GFCI outdoor outlet, and the discharge hose must be routed far enough away to prevent water from recycling back under the deck.

Line Blower – Cyclone Pro Commercial Bypass Blower

A standard shop vac rarely has the air volume or pressure required to clear water out of deep pool lines, especially the main drain at the bottom of the deep end. Leaving water in these lines is a recipe for catastrophic underground pipe failure. The Cyclone Pro Commercial Bypass Blower is designed specifically to conquer the backpressure of deep pool water, forcing air through the entire system with ease.

Equipped with a powerful bypass motor, this blower can run continuously without overheating, even when the air outlet is restricted by deep water resistance. This consistent air volume ensures a complete blowout, leaving no hidden pockets of water to freeze and crack your plumbing.

• Motor: 3.0 HP bypass motor with thermal protection.
• Hose: 1.5-inch flexible hose with quick-connect fittings.
• Pressure Output: Capable of clearing lines up to 15 feet deep.

While this is a premium tool with a higher upfront cost, it pays for itself in just two seasons by eliminating the need to hire a professional pool closing service. It is highly recommended for DIY pool owners who want absolute certainty that their underground lines are bone-dry.

Balancing Your Pool Chemistry Before the Freeze

Many pool owners mistakenly think chemical balancing is only important when the pool is open for swimming. In reality, water chemistry behaves differently in cold temperatures, and unbalanced water can cause severe etching to plaster or scale build-up on vinyl over the winter months. Before you add any winterizing chemicals, your water must be perfectly balanced to prevent these slow-moving chemical reactions.

Begin by adjusting your pH to 7.2–7.6 and your total alkalinity to 80–120 ppm. It is also critical to verify your calcium hardness levels, keeping them between 200 and 400 ppm; water that is too soft will leach calcium directly out of plaster and grout during its long winter sleep.

Once these baseline levels are secure, shock the pool with chlorine or a non-chlorine alternative a few days before closing. Let the filtration system circulate the clean water thoroughly, allowing the chlorine levels to drop back to normal operating ranges before adding your winter algaecides and stain preventers. This prevents high chlorine levels from neutralizing the long-term winter chemicals you rely on.

How to Safely Blow Out and Plug Your Pool Lines

Blowing out your plumbing lines is the most critical technical step in the winterization process. The sequence is vital: you must work systematically from the shallowest lines to the deepest to ensure water is pushed out completely and not just shifted to another part of the system. Always start by lowering the pool water level below the skimmer mouth if your winter cover style requires it.

Connect your line blower to the pump basket or the skimmer line and turn it on to force air through the system. Watch for a steady stream of air bubbles exiting the return lines, and quickly insert your expansion plugs while the air is actively blowing to lock water out. Once the return lines are sealed, divert the air flow to the main drain at the bottom of the pool until it bubbles like a geyser.

The trick to the main drain is creating an air lock. Since you cannot easily plug a main drain under ten feet of water, you must close the valve at the pool pad while the air is blowing furiously. This traps a column of pressurized air inside the pipe, preventing water from rising back up into the freezing zone of your plumbing.

Mid-Winter Maintenance Tasks You Cannot Ignore

Closing your pool does not mean you can ignore it until May. Mid-winter neglect is a primary cause of cover damage and water contamination, especially after severe winter storms. A quick bi-weekly inspection of your backyard pool area can catch small issues before they escalate into expensive spring repairs.

Keep a close eye on your cover tension. Heavy snow loads and high winds can stretch safety cover springs to their limit, requiring manual adjustments to keep the mesh tight and off the water surface. If you use a solid cover, make sure your cover pump is clear of leaves and operating properly after heavy rain or snowmelt.

Finally, peek under the cover once or twice during the winter to check the actual water level. A slow, undetected leak can cause the pool water level to drop, leaving your safety cover to support its own weight without the buoyant assistance of the water beneath it. If the water drops significantly, it can warp your cover anchors or even collapse your pool walls under a heavy snow load.

Taking the time to winterize your pool with the right gear ensures your backyard investment remains protected against the harshest winter weather. By combining robust physical barriers with balanced chemistry and clear lines, you set yourself up for an effortless, crystal-clear spring opening. Keep these tips in mind, protect your equipment, and enjoy a worry-free winter season.