8 Essential Pool Closing Supplies for Winterizing in Freezing Climates

Watching the first autumn leaves drift onto your pool deck is a clear signal that the swimming season is coming to an end. In freezing climates, failing to prepare your backyard pool for sub-zero temperatures can result in thousands of dollars in ruptured pipes and cracked concrete. Equipping yourself with the right winterizing supplies now guarantees a stress-free reopening when warm weather returns next spring.

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Why Freezing Climates Require Proper Pool Closing

Water expands by approximately nine percent when it freezes, exerting immense pressure on anything containing it. In a swimming pool, this expansion can crack thick concrete shells, split PVC plumbing lines, and ruin delicate filtration equipment overnight. Failing to winterize properly in northern climates is essentially gambling with the structural integrity of your backyard investment.

Proper winterization creates a controlled environment that mitigates this freeze-thaw damage while keeping organic debris out of the pool water. It involves a systematic approach of lowering water levels, clearing plumbing lines, and applying chemical treatments to prevent algae growth under the cover. Skipping even one of these steps can turn a simple spring opening into a costly, labor-intensive renovation project.

Safety Cover – Loop-Loc Green Mesh Safety Pool Cover

A safety cover is the primary defense system for an inground pool during the harsh winter months. Unlike cheap tarps weighed down by water bags, a safety cover stretches taut across the pool, anchored securely into the deck. It prevents heavy snow loads from collapsing into the pool while keeping children, pets, and stray wildlife from falling into the freezing water.

The Loop-Loc Green Mesh Safety Pool Cover is the gold standard because of its legendary “bounce-back” strength and high-density mesh design. The mesh material allows rainwater and melting snow to drain through into the pool, preventing dangerous water accumulation on top of the cover. It blocks ultra-violet light to suppress winter algae growth, while the super-strong polyester bonding thread ensures the seams never unravel under heavy snow loads.

• Available Sizes: 16×32 ft to 20×40 ft standard, custom shapes available
• Material: High-density mesh with polyester bonding thread
• Weight Capacity: Engineered to support up to 4,000 pounds

When purchasing, accurate pool measurements are critical since these covers are designed for specific pool shapes and step configurations. Installing concrete or wood deck anchors requires drilling, meaning a rotary hammer drill is an essential companion tool for the initial setup. Keep in mind that fine silt can pass through the mesh, meaning some vacuuming will be required upon spring opening.

This cover is best for homeowners in high-snow regions who prioritize safety and want a cover that lasts for decades. It is not designed for above-ground pool configurations or budget-conscious pool owners who prefer a solid tarp that blocks 100% of fine dirt and water.

Pool Air Pillow – Robelle Ice Equalizer Pillow

Above-ground pools face a unique threat from freezing water, which expands outward and can crush the pool’s metal walls like an aluminum can. An air pillow sits in the center of the water under the cover, acting as an artificial expansion joint. When the surface ice expands inward, it compresses the pillow instead of pushing outward against the pool’s structural walls.

The Robelle Ice Equalizer Pillow stands out because it utilizes heavy-duty 16-gauge vinyl that resists puncturing under intense freeze pressure. Cheaper pillows frequently pop mid-winter due to thin seams, but this model features double-welded seams designed to withstand extreme cold. It also includes built-in grommets on the corners, allowing for secure centering in the pool.

• Available Sizes: 4×4 ft, 4×8 ft, 4×15 ft
• Material: 16-gauge heavy-duty vinyl
• Connection Points: Four reinforced corner grommets

The golden rule of pool pillows is to inflate them to only about 60% to 70% capacity. Over-inflating them leaves no room for compression, which causes them to burst when the ice closes in. Users should tie ropes through the corner grommets to anchor the pillow directly in the center of the pool before laying down the cover.

This product is ideal for above-ground pool owners in regions with sustained freezing temperatures who need to protect their pool walls. It is not necessary for inground pool owners, as inground structures do not suffer from the same outward wall-crushing forces.

Winterizing Kit – In The Swim Ultimate Winter Kit

Closing a pool with balanced, treated water prevents staining, scaling, and massive algae blooms from taking over during the long off-season. A specialized winterizing kit provides pre-measured chemical components designed to work in cold, dark conditions under the pool cover. This ensures the water remains clear and manageable, saving hours of scrubbing and chemical balancing in the spring.

The In The Swim Ultimate Winter Kit is the ultimate choice because of its comprehensive, time-released formula. It includes a powerful winterizer algaecide, a non-chlorine shock, and a slow-dissolving Winterizer Floating Dispenser that continually sanitizes the water. The inclusion of a pool winterizing stain preventer ensures that mineral deposits do not etch the pool walls during months of stagnation.

• Kit Capacities: Up to 10,000, 20,000, and 35,000 gallons
• Included Chemicals: Winter shock, winterizer algaecide, stain preventer
• Dispensing Method: Time-release floating dispenser

These kits are sized based on total pool gallonage, so knowing the exact volume of your pool is crucial before purchasing. The chemicals should be added to the pool after the water level has been lowered but while the filtration pump is still running to ensure thorough mixing.

This kit is best for pool owners wanting an all-in-one, pre-measured chemical solution to prevent green water and staining during winter. It is not right for owners of very small splash pools or those who prefer to source and mix their own bulk chemicals individually.

Winter Expansion Plug – Anderson Winterizing Plug

Once the water is cleared from the underground plumbing lines, those lines must be sealed to prevent water from seeping back in and freezing. Winter expansion plugs are inserted into return lines and cleaner lines to create a watertight seal. If a plug leaks, water will re-enter the pipe, freeze, and cause underground pipe ruptures that are incredibly expensive to locate and repair.

The Anderson Winterizing Plug utilizes a premium rubber compound that remains flexible even in sub-zero temperatures, ensuring the seal does not dry out or crack. The heavy-duty nylon wing nut and non-corrosive hardware allow for high-torque tightening without stripping the threads. This guarantees a reliable, airtight seal that withstands the pressure of expanding ice within the pool shell.

• Available Sizes: #8 (1.5 inches) to #11 (2 inches) standard expansion sizes
• Material: Heavy-duty rubber with nylon wing nuts
• Application: Inlet lines, return lines, cleaner lines, and skimmer ports

Plugs are sold in various numbered sizes corresponding to the diameter of your return jets, so measuring your fittings is a necessary first step. Applying a thin coat of water-soluble pool lubricant to the rubber before insertion helps create a smoother, more effective seal.

This plug is best for inground pool owners looking for commercial-grade, reliable line sealing that will not degrade over winter. It is not for pools with threaded fittings that are better suited for threaded male plugs, or above-ground pools that drain below the return lines completely.

Skimmer Guard – Gizzmo Skimmer Protection Device

The skimmer box is one of the most vulnerable parts of an inground pool because water naturally accumulates there and freezes quickly. As this trapped water expands, it can easily crack the plastic skimmer throat, leading to devastating leaks behind the pool wall. A skimmer guard absorbs this freeze expansion and seals the skimmer line from the top down.

The Gizzmo Skimmer Protection Device is the industry standard because of its unique, hollow, compressible design. It features a heavy-duty plastic body with a threaded male end that screws directly into the bottom of the skimmer line. If ice forms inside the skimmer, the Gizzmo collapses inward, absorbing the destructive pressure that would otherwise crack the skimmer housing.

• Thread Sizes: 1.5-inch and 2-inch male pipe threads
• Lengths Available: 9-inch (standard) and 16-inch (super)
• Material: High-density compressible polyethylene

The Gizzmo comes in different lengths and thread sizes, typically 1.5-inch or 2-inch threads, making compatibility checks essential before purchase. Wrapping Teflon tape around the Gizzmo’s threads ensures a watertight seal and makes removal in the spring much easier.

This device is best for inground pool owners with standard skimmers who want to protect their skimmer wells from ice damage without draining the pool completely. It is not suited for above-ground pools with small, external skimmers that can easily be disconnected and stored indoors.

Pool Cover Pump – Little Giant APCP-1700 Pump

If you use a solid tarp cover, rain and melting snow will inevitably accumulate on top, creating a heavy pool of water. This excess weight strains the cover, pulls anchors out of the deck, and can even compromise the pool walls. A pool cover pump automatically removes this standing water before it freezes into a massive, heavy sheet of ice.

The Little Giant APCP-1700 Pump is the ultimate choice because of its automatic freeze-protection switch. It activates automatically when water levels reach two inches and shuts off when the water is gone, meaning no manual monitoring is required. It features a removable intake screen that prevents leaves and twigs from clogging the impeller, which is critical during autumn leaf drops.

• Flow Rate: Up to 1,700 gallons per hour
• Cord Length: 25-foot heavy-duty power cord
• Discharge Connection: Standard 3/4-inch garden hose thread

This pump must be connected to a standard garden hose to route the discharged water away from the pool deck. Users should ensure the hose does not have kinks and is angled downhill to prevent water from freezing inside the discharge line.

This pump is best for owners of solid safety covers or traditional solid winter tarps who need reliable, hands-off water removal. It is not for owners of mesh safety covers, as water drains directly through the mesh and does not pool on top of the cover.

Pool Antifreeze – Splash Non-Toxic Antifreeze

Even after blowing out the plumbing lines, small pockets of water can remain trapped in low spots or elbows of underground pipes. Pool antifreeze is added to these lines to prevent any residual water from freezing and cracking the PVC. It acts as a safety net, ensuring that your hard work blowing out the lines is not undone by a small amount of condensation or runoff.

Splash Non-Toxic Antifreeze is formulated with high-purity propylene glycol, making it safe for pool plumbing and environmentally friendly. Unlike automotive antifreeze, which is highly toxic ethylene glycol, this formula is safe for family swim areas and will not damage pool liners or plumbing gaskets. It provides burst protection down to -50 degrees Fahrenheit, giving peace of mind during the deepest winter freezes.

• Base Ingredient: High-purity propylene glycol
• Temperature Rating: Burst protection down to -50°F
• Safety Rating: Non-toxic, GRAS (Generally Recognized as Safe) formula

Never add pool antifreeze directly to the pool water; it is strictly intended for plumbing lines. When spring arrives, this non-toxic fluid can be safely flushed into the pool and filtered out, or vacuumed out depending on local regulations.

This product is best for inground pool owners in deep-freeze climates who want insurance against residual water freezing in underground pipes. It is not for pool owners in mild climates where temperatures rarely drop below freezing, or simple above-ground setups where lines are disconnected.

Pool Leaf Net – Blue Wave Bronze Leaf Net Cover

Deciduous trees drop a massive volume of leaves during late autumn, right around the time you close your pool. If these leaves decompose on top of your pool cover, they create a heavy, rotting sludge that is incredibly difficult to clean in the spring. A leaf net is laid over the main winter cover and peeled off once all the trees are bare, leaving a clean cover underneath.

The Blue Wave Bronze Leaf Net Cover features an exceptionally durable polyethylene mesh that resists tearing from sharp twigs and heavy winds. It is constructed with an extra-wide overlap, ensuring complete coverage even on pools with wide top rails. The lightweight design makes it easy for two people to lift and shake off, even when loaded with wet, heavy leaves.

• Available Shapes: Round, Oval, Rectangular
• Overlap Allowance: 3-foot overlap to fit secure anchors
• Material: Woven polyethylene mesh with reinforced binding

Timing is everything with a leaf net; it must be installed immediately after closing and removed as soon as the last leaves fall, but before the first major freeze. If the leaves freeze to the net, it becomes too heavy to lift and can damage the underlying cover.

This net is best for pool owners with heavy deciduous tree cover nearby who want to avoid messy spring cleanup on top of their winter cover. It is not for homeowners without nearby trees or those who live in areas where winter weather goes straight from summer to heavy snow without a prolonged autumn leaf drop.

How to Properly Blow Out Your Pool Plumbing Lines

Blowing out the plumbing lines is the most critical step in preventing freeze damage to underground pipes. Start by lowering the pool water level below the skimmer mouth to prevent water from re-entering the lines during the process. Connect a high-volume air blower or a heavy-duty shop vacuum to the pool pump basket or the main return line to push air through the system.

Watch the pool return jets closely; as air is forced through, you will see a massive eruption of water followed by a steady stream of air bubbles. Once only air is escaping, quickly insert your winter expansion plugs into the return jets to seal them off under pressure. Repeat this process for the skimmer lines, securing each with a skimmer guard or plug while the air is still blowing.

Finally, address the main drain line by pushing air until bubbles emerge from the bottom of the pool, then quickly close the valve at the equipment pad to lock in an air pocket. This airlock prevents water from rising back up into the pipe, utilizing the natural physics of trapped air to protect the deepest plumbing lines from freezing.

Managing Pool Water Chemistry Before the Hard Freeze

Balanced water chemistry is your best defense against staining, scaling, and biological growth during the long winter hibernation. Several days before closing, test and adjust the pH to between 7.2 and 7.6, and ensure the total alkalinity rests between 80 and 120 parts per million. This baseline balance prevents the water from becoming acidic and etching pool plaster, or basic and forming scale on tile lines.

Once balanced, add a high-quality winterizing shock to eliminate organic contaminants and clear out any lingering bacteria. Allow the filtration system to run for at least 24 hours to distribute these chemicals evenly throughout the entire pool volume. Finally, add your winter algaecide to prevent spores from taking hold as the water temperatures drop.

Avoid adding chlorine shock and algaecide at the exact same time, as high chlorine levels can destroy the active ingredients in the algaecide. Wait until the chlorine level drops back to normal operating range before adding the final dose of algaecide and installing the pool cover.

Storing Filtration Equipment and Pumps for Winter

Leaving water inside filtration equipment during a hard freeze is a guaranteed way to crack expensive housings and pump volutes. Begin by turning off all power at the breaker panel and disconnecting any automated control systems. Open the drain plugs at the bottom of the filter tank, pump basket, and heater to allow all trapped water to drain out completely.

For cartridge and diatomaceous earth (DE) filters, remove the internal elements or grids, spray them clean, and store them in a dry, rodent-proof area. If you have a sand filter, leave the drain plug off so any internal moisture can evaporate over the winter. Store all removed drain plugs in the pump basket so they do not get lost before spring startup.

If possible, disconnect the pool pump motor entirely and store it indoors in a basement or heated garage to protect the electrical components from condensation. For stationary heaters and salt cells, blow out any internal plumbing chambers with air and apply protective winter covers to keep out nesting pests and debris.

Taking the time to properly winterize your pool with high-quality supplies is the ultimate insurance policy against cold-weather damage. By securing your plumbing lines, balancing your water chemistry, and deploying durable covers, you protect your backyard investment through the harshest winter conditions. When the spring thaw finally arrives, you will be rewarded with a clean, undamaged pool that is ready for another season of fun.