8 Essential Pool Closing Supplies for Winter Protection

As the autumn leaves begin to fall and the evening air turns crisp, the window for safeguarding your backyard investment starts to close. Failing to prepare your swimming pool for sub-freezing temperatures can lead to cracked plumbing, ruptured filtration tanks, and torn liners that cost thousands of dollars to repair. Equipping yourself with the right seasonal gear ensures your pool survives the harshest winter elements and remains ready for a hassle-free spring opening.

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Why Proper Winterization Prevents Costly Freeze Damage

When water freezes, it expands by approximately nine percent, exerting immense physical pressure on everything containing it. In a backyard pool, this expansion can easily crack heavy-duty PVC underground pipes, split open concrete skimmer wells, and rupture expensive filter tanks. A proper winterization routine creates space for this expansion to occur harmlessly while isolating vulnerable plumbing lines from water intrusion.

Beyond mechanical damage, winter brings debris, algae growth, and heavy snow loads that threaten the structural integrity of your pool walls and liner. Unsecured covers can collapse under the weight of accumulated ice, pulling down pool walls or tearing vinyl liners. Taking the time to properly seal, balance, and cover the pool before the first hard freeze saves countless hours of scrubbing and thousands of dollars in structural repairs come spring.

Winter Pool Cover – Robelle Super Winter Cover

A heavy-duty winter cover is your pool’s primary shield against rotting leaves, windblown debris, and harsh winter sunlight, which fuels algae growth. Without a solid barrier, your pool water quickly turns into a swampy, organic soup that requires extensive chemical treatments to clear up in the spring. It also prevents wind from evaporating balanced pool water during the dry winter months.

The Robelle Super Winter Cover stands out because of its heavy-duty polyethylene construction and tight material weave, which effectively blocks both debris and sunlight. It features a water-resistant top coating and a black underside to inhibit algae photosynthesis throughout the off-season. Secure grommets are placed every four feet, allowing for a tight, reliable tie-down that resists flapping in heavy winter winds.

Key Specifications:

• Material: Heavy-duty polyethylene
• Scrim Count: 8×8 strands per square inch
• Overlap: 4-foot overlap included for secure anchoring
• Color Options: Multi-color tops with black underside to block light

When choosing this cover, make sure to order based on your actual pool size, as the manufacturer already includes the necessary overlap. For in-ground pools, you will need water blocks or tubes to weigh down the perimeter, while above-ground pools require a cable and winch system to secure the cover tightly below the top rail. Keep in mind that this is a solid cover, meaning water will accumulate on top and require periodic pumping.

This cover is ideal for pool owners in regions with heavy tree cover and long, freezing winters who want a reliable, budget-friendly shield. It is not suitable for those looking for a safety-rated cover that can support the weight of wandering pets or children—for that, a tension-secured safety cover is required.

Pool Air Pillow – Swimline Ice Equalizer Pillow

For above-ground pools, ice formation is a silent killer of structural walls. When a solid sheet of ice forms across the pool surface, it exerts outward lateral pressure against the pool walls, which can warp the metal frame or split the vinyl liner. An air pillow sits in the center of the pool under the cover, acting as a sacrificial pressure absorber that compresses as the ice expands inward.

The Swimline Ice Equalizer Pillow is manufactured from heavy-gauge vinyl designed to withstand extreme cold without becoming brittle and popping. Its rugged valves prevent slow air leaks, ensuring the pillow remains inflated under the heavy weight of snow and ice all winter long. By creating a peak in the center of your cover, it also helps channel rainwater and melting snow toward the edges for easier removal.

Key Specifications:

• Material: Heavy-gauge, cold-resistant vinyl
• Dimensions: Available in 4’x4′, 4’x8′, and 4’x15′ sizes
• Valve Type: Secure-seal leak-resistant valve
• Grommets: Reinforced corner eyelets for securing strings

To use this pillow correctly, only inflate it to 60 to 70 percent capacity; a fully inflated pillow will pop under the immense pressure of freezing ice. Tie the pillow loosely to opposite sides of the pool so it stays centered rather than drifting to one wall. It is compatible with all above-ground pool covers but must be secured before the cover is completely pulled over the pool.

This product is a must-have for above-ground pool owners in areas that experience prolonged freezing temperatures. It is generally unnecessary for in-ground pools, where the surrounding soil absorbs the lateral pressure of freezing surface ice.

Skimmer Guard – Gizzmo Ultra Freeze Protection Device

The skimmer box is one of the most vulnerable components of an in-ground or above-ground pool because it sits right at the water level and has thin plastic walls. If water freezes inside the skimmer, the expanding ice will crack the throat of the skimmer, leading to a major leak that requires tearing up concrete deck space to repair. A skimmer guard absorbs this expansion while sealing off the plumbing line below.

The Gizzmo Ultra Freeze Protection Device combines a heavy-duty, hollow plastic tube with integrated threads that screw directly into the bottom of the skimmer. The sealed, air-filled chamber collapses under the pressure of freezing water, saving the skimmer housing from cracking. It features a built-in blowout channel that allows you to clear the plumbing lines without removing the device.

Key Specifications:

• Material: High-density, crush-resistant plastic
• Thread Size: Available in 1.5-inch and 2-inch tapered threads
• Design: Hollow core with relief valve to absorb expansion
• Length: Extended length for deep skimmer wells

The Gizzmo is available in different thread sizes, typically 1.5-inch or 2-inch options, so checking your skimmer’s plumbing port size before buying is critical. Wrap the threads with Teflon tape to ensure a watertight seal before screwing it in. Ensure the unit is screwed in snugly but not overtightened, which can strip the plastic threads of the skimmer housing.

This device is essential for any pool owner with a skimmer box in a freezing climate who wants a simple, dual-action solution for plugging the line and absorbing ice expansion. It is not designed for pools in tropical climates where freezing is never a concern.

Expansion Plug – Hayward Rubber Expansion Plug

Once plumbing lines are cleared of water, they must be sealed airtight to prevent water from seeping back into the pipes from the pool. If water enters the return jets during a heavy winter storm, it will freeze and crack the pipes underground. Expansion plugs fit inside the wall returns and step-jets to create a positive, airtight seal.

The Hayward Rubber Expansion Plug features a heavy-duty, industrial-grade rubber body with non-corrosive nylon wing nuts and stainless steel bolts. As you tighten the wing nut, the rubber compression sleeve expands to create a completely airtight and watertight seal inside the pipe. The nylon hardware ensures that the plug will not rust or seize up, making them easy to remove in the spring.

Key Specifications:

• Material: Heavy-duty, chemical-resistant rubber
• Hardware: Non-corrosive nylon wing nut and stainless steel bolt
• Sizing: Fits standard 1.5-inch and 2-inch pool return lines
• Design: Tapered shape for a secure fit

These plugs come in various sizes, with No. 8, No. 9, and No. 10 being the most common for standard pool returns. Measuring the inside diameter of your return lines or step jets is necessary to ensure a snug fit. Always check the rubber for cracking or dry rot before reinstalling them each autumn, replacing them as needed to avoid winter leaks.

This plug is a critical safety item for any pool owner looking to seal off return lines, suction lines, or cleaner lines. It is not suitable for threaded pipes unless you purchase the specific threaded adapter version, as smooth rubber plugs can slip out under high pressure.

Pool Antifreeze – Splash Non-Toxic Antifreeze

Even after blowing out the plumbing lines, small pockets of water can migrate back down into low spots in the pipes or filtration equipment. If this residual water freezes, it can split underground pipes or crack valve bodies. Pouring pool-specific antifreeze into the lines adds an extra layer of defense by lowering the freezing point of any lingering water.

Splash Non-Toxic Antifreeze is formulated specifically for swimming pools and recreational vehicles, utilizing non-toxic propylene glycol rather than toxic ethylene glycol used in automotive applications. It is rated to protect plumbing down to -50 degrees Fahrenheit, providing peace of mind during extreme winter cold snaps. Because it is non-toxic, it will not harm swimmers or balance levels when the pool is reopened and the lines are flushed in the spring.

Key Specifications:

• Base Ingredient: Propylene Glycol (non-toxic)
• Temperature Rating: Safe down to -50°F (-45°C)
• Application: Plumbing lines, pump housings, and filtration equipment
• Safety: Safe for vinyl, PVC, and copper plumbing

Never use automotive antifreeze in a swimming pool, as it is highly toxic to humans and pets and will ruin your pool filtration system. One gallon of pool antifreeze is typically required for every 10 to 15 feet of pipe being treated. Ensure the lines are blown out as much as possible before adding the antifreeze, as heavy water dilution will reduce its temperature rating.

This product is highly recommended for pool owners in severe northern winter climates where ground-freeze depths exceed a few inches. It is unnecessary for pools in mild southern climates that rarely experience sustained freezing temperatures.

Winter Chemical Kit – In The Swim Ultimate Winter Kit

Closing a pool is not just about physical protection; it is also about chemical preservation. Over the long winter months, stagnant water can host algae blooms, mineral scaling, and stain-causing metal oxidation. A dedicated winter chemical kit slowly releases protective compounds to keep the water clear and chemically balanced until spring.

The In The Swim Ultimate Winter Kit provides a comprehensive, pre-measured chemical package containing a winterizing oxidizer, a long-lasting algaecide, metal stain removers, and a slow-releasing chemical dispenser. This multi-stage kit is designed to work in cold water, preventing the common “green pool” opening scenario that plagues many pool owners. The components are safe for all pool types, including plaster, vinyl, and fiberglass.

Key Specifications:

• Kit Contents: Winterizing oxidizer, algaecide, stain away, and chemical dispenser
• Pool Size Options: Kits for pools up to 10k, 20k, and 35k gallons
• Compatibility: Safe for vinyl, plaster, concrete, and fiberglass pools
• Duration: Formulated to last up to 6 months of off-season storage

These kits are sold by pool volume, with common sizes protecting pools up to 10,000, 20,000, or 35,000 gallons. It is important to know your exact pool capacity to avoid under-treating the water, which leads to algae growth by early spring. Always dissolve dry chemicals in a bucket of water before pouring them into the pool to prevent bleaching your liner.

This kit is perfect for pool owners who want an all-in-one chemical solution to guarantee a clean, clear pool opening in the spring. It is not necessary for pool owners who prefer to custom-mix their own winter chemical recipes using bulk supplies.

Pool Cover Pump – Little Giant APCP-1700 Cover Pump

Solid winter pool covers inevitably collect rain, melting snow, and rotting wet leaves over the winter months. If left unmanaged, this heavy accumulation of water creates massive stress on the cover straps, anchors, and pool walls. It also creates a safety hazard and a breeding ground for early-spring mosquitoes.

The Little Giant APCP-1700 Cover Pump is a submersible pump featuring an integrated mechanical float switch that automatically turns the pump on when water reaches a depth of two inches and shuts off when it is drained. It can move up to 1,700 gallons of water per hour, making quick work of heavy winter downpours. The wide, stable base prevents the pump from tipping over on the uneven surface of a soft pool cover.

Key Specifications:

• Flow Rate: Up to 1,700 gallons per hour (GPH)
• Switch Type: Automatic mechanical float switch
• Power Cord: 25-foot heavy-duty power cord
• Discharge Connection: Standard 3/4-inch garden hose threads

The pump connects to a standard garden hose for drainage and features an extra-long 25-foot power cord to reach outdoor GFCI outlets safely. Keep the intake screen free of leaves and pine needles, which can clog the impeller and cause the pump motor to overheat. It is designed to be left on the cover all winter, but should be removed if a deep freeze is predicted to prevent the pump housing itself from freezing.

This pump is a must-have for anyone using a solid winter cover or safety cover that collects standing water. It is not needed for pool owners with mesh safety covers, which allow rainwater to drain directly into the pool.

Pool Water Bag – Swimline Double Water Tube

In-ground pools using solid covers require a heavy, reliable anchoring system around the perimeter to keep the cover from blowing away or sliding into the pool under a snow load. Placing bricks, concrete blocks, or lumber on the cover can permanently damage or tear the vinyl fabric. Water bags provide a soft, heavy, and harmless weight that conforms to the pool deck.

The Swimline Double Water Tube is constructed from heavy-gauge, puncture-resistant vinyl designed to handle freezing temperatures without splitting. The double-chamber design prevents the tube from rolling off the deck and into the pool, which is a common issue with single-chamber designs. Even if one side of the double tube manages to leak or puncture, the remaining chamber keeps the cover anchored.

Key Specifications:

• Material: Heavy-duty, puncture-resistant vinyl
• Design: Double-chamber configuration to prevent rolling
• Length Options: Available in 8-foot and 10-foot lengths
• Valves: Leak-resistant snap-cap valves

When filling these water bags, only fill them halfway to two-thirds full to allow room for the water to expand as it freezes into ice. Overfilling them will cause the seams to split open during the first deep freeze, rendering them useless. Space them continuously around the perimeter of the pool cover to ensure wind cannot get underneath and lift the cover.

This is a vital product for any in-ground pool owner utilizing a standard solid tarp-style winter cover. It is not necessary for above-ground pool covers or in-ground pools fitted with anchored spring-tension safety covers.

How to Blow Out Your Pool Lines Before the First Freeze

Blowing out the plumbing lines is the most critical step in preventing freeze damage to underground pipes. Start by lowering the water level in your pool to about six inches below the skimmer mouth. Connect a high-volume air compressor or a specialized pool line blower to the pump basket plumbing port, ensuring all valves are set to direct air toward the pool returns.

As the air forces water out of the returns, you will see a massive bubbling action in the pool. Once the line is completely cleared of water and only blowing air, quickly slide your rubber expansion plug into the return fitting and tighten it securely to seal the line. Repeat this process for each return line, suction line, and main drain, working from the closest line to the furthest.

For the main drain at the bottom of the pool, blow air through the line until you see bubbles rise from the deep end, then quickly close the valve at the equipment pad to create an air lock. This air lock prevents water from rising back up the pipe, keeping it safe from freezing without needing a physical plug deep underwater.

Balancing Water Chemistry for Long-Term Off-Season Storage

Many pool owners make the mistake of closing their pools with unbalanced water, leading to severe plaster etching, metal staining, or vinyl degradation by spring. Before adding any winter chemicals, test and adjust the pH to between 7.2 and 7.6, and ensure the total alkalinity sits between 80 and 120 parts per million. Balanced water prevents corrosive reactions from occurring while the pool filtration system is offline for months.

Calcium hardness should also be adjusted to a range of 200 to 400 parts per million to protect plaster and tile grout from dissolving into calcium-starved winter water. Once the basic parameters are set, shock the pool with chlorine to eradicate any lingering algae spores, letting the chlorine level return to normal before adding your winter algaecide and cover.

Keep the pool pump running for at least 24 hours after adding these balancing chemicals to ensure complete circulation throughout the entire body of water. This thorough mixing prevents concentrated pockets of chemicals from settling on the pool floor, which can bleach vinyl liners or damage plaster finishes.

Mid-Winter Maintenance Checks to Protect Your Equipment

Closing the pool does not mean you can ignore it until spring arrives. A monthly inspection of your winter cover, water tubes, and surrounding deck can catch minor issues before they turn into expensive disasters. Check the tension of your cover cable or safety spring anchors to make sure the cover remains taut and secure against heavy winter winds.

Inspect the water level under the cover to ensure there are no slow leaks in your liner; a dropping water level removes the physical support for the winter cover, which can cause the cover to collapse into the pool. Clear off any heavy snow accumulation from above-ground pool covers gently using a soft broom rather than a metal shovel, which can puncture the cover fabric.

Finally, check that your skimmer guards and expansion plugs remain tightly seated. Fluctuating temperatures can sometimes cause plastic and rubber fittings to contract, loosening the seal and allowing water back into the plumbing lines. Spending fifteen minutes on a mid-winter check ensures your pool remains fully protected through the coldest weeks of the year.

Conclusion

Preparing your backyard pool for the off-season requires the right combination of protective gear, chemical balance, and careful execution. By investing in reliable winterization tools, you protect your valuable equipment from costly freeze damage and make spring opening a breeze. Take the time to secure your lines, cover your pool, and monitor it through the cold months to ensure a seamless transition back to swim season.