9 Essential Winter Pool Closing Supplies for a Backyard Pool

As autumn leaves begin to fall and the summer heat fades, the backyard pool transforms from a sparkling oasis into a maintenance responsibility that cannot be ignored. Skipping or rushing the winterization process invites cracked pipes, ruined liners, and a swampy green mess come springtime. Arming yourself with the correct winter closing supplies is the single best way to protect this valuable backyard investment and ensure an effortless opening next season.

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Why Proper Winterization Saves Your Pool Investment

Freezing temperatures are a pool’s worst enemy. When water freezes, it expands by about nine percent, exerting immense pressure on everything from underground PVC pipes to the pool’s concrete or vinyl shell. Without proper winterization, this expansion can cause underground line splits that cost thousands of dollars to excavate and repair.

Beyond structural damage, leaving a pool improperly closed invites algae blooms and organic staining that can permanently ruin a vinyl liner or mar a plaster finish. A pool left open to the elements accumulates leaves, twigs, and debris, which decay and deplete any remaining chlorine. By investing in the right closing gear, pool owners prevent costly structural failures and avoid spending hundreds of dollars on rescue chemicals in the spring.

Proper winterization also preserves the mechanical integrity of pumps, filters, and heaters. Water trapped inside these expensive components can freeze and crack pump housings or heat exchangers overnight. Taking the time to execute a thorough winter shutdown keeps your equipment operational for its intended lifespan, ensuring you are ready to swim the moment warm weather returns.

Winter Pool Cover – Robelle Super Winter Cover

A heavy-duty winter cover is the primary shield defending a pool from heavy snow, high winds, and decaying organic debris. Without a solid barrier, sunlight penetrates the water, fueling rapid algae growth even in cooler temperatures, while autumn leaves turn the pool water into a dark, tannin-rich tea. A reliable cover keeps the pool interior clean, dark, and chemically stable throughout the off-season.

The Robelle Super Winter Cover stands out due to its heavy-duty polyethylene construction and its dense 8×8 scrim count, which provides exceptional puncture resistance and durability. The top side is treated to resist damaging ultraviolet rays, while the black underside prevents sunlight from reaching the water to suppress algae growth. It features a generous four-foot overlap to accommodate water level drops, ensuring the cover does not pull taut and slip into the pool under the weight of snow.

When selecting this cover, always order based on the actual pool size, as the manufacturer already includes the necessary overlap in the sizing. Standard configurations include: * Round above-ground sizes from 12 to 30 feet * Oval above-ground sizes to fit common footprints * In-ground rectangular sizes with heavy-duty securing grommets

Using a cover that is too small will put immense stress on the seams when snow accumulates, potentially causing a catastrophic failure mid-winter.

This cover is ideal for pool owners who face harsh winters with heavy leaf fall and snow accumulation. It is not designed for those looking for a tension safety cover that can support the weight of roaming pets or children; for that level of safety, a dedicated safety mesh cover with deck anchors is required.

Pool Air Pillow – Swimline 4×4 Foot Pillow

An air pillow, or ice equalizer, is crucial for above-ground pools because it relieves the pressure that freezing water exerts on the pool walls. As the surface water freezes into a solid sheet of ice, it expands outward, pushing against the pool’s metal framework and liner. An air pillow sits in the center of the pool, compressing to absorb this outward pressure and protecting the pool structure from collapsing inward.

The Swimline 4×4 Foot Pillow is built from heavy-gauge vinyl designed to withstand freezing temperatures without cracking or leaking air. Its 10-gauge vinyl construction provides a reliable cushion that remains pliable even when the thermometer dips below zero. It features reinforced grommets on all four corners, allowing for easy centering using nylon ropes tied to the pool coping.

To ensure the pillow survives the winter, only inflate it to about 60% to 70% of its capacity. Over-inflating the pillow leaves no room for compression, causing the seams to pop the moment ice begins to expand or snow piles onto the cover. Additionally, securing it dead-center is critical; if the pillow drifts to one side, it will not protect the opposite wall from ice expansion.

This pillow is a necessity for any above-ground pool owner in regions where the ground freezes solid. It is not necessary for in-ground pools, which rely on different freeze-protection methods like water bags and skimmer guards.

Winterizing Chemical Kit – In The Swim Winter Kit

Closing a pool with balanced water is only half the battle; the water must remain treated throughout the long winter months to prevent staining and biological growth. A winterizing chemical kit provides a slow-release system that preserves water quality under the cover. This ensures that the water remains clear and free of scale, preventing the need for massive chemical corrections in the spring.

The In The Swim Winter Kit is a smart choice because it contains pre-measured, highly compatible chemicals designed to work in cold, stagnant water. The kit includes a phosphorus-free winterizer, a powerful metal stain preventer, and a slow-releasing non-chlorine winter oxidizer dispenser. This combination prevents calcium buildup on the pool walls and destroys organic contaminants without bleaching vinyl liners.

Kits are sized specifically by pool volume, making it simple to get the exact dosage needed: * Small Kit: Treats pools up to 10,000 gallons * Medium Kit: Treats pools up to 20,000 gallons * Large Kit: Treats pools up to 35,000 gallons

Before adding the kit, ensure the water pH is balanced between 7.2 and 7.6, and run the pool filter for at least four hours to distribute the chemicals evenly before lowering the water level.

This kit is perfect for pool owners who want a straightforward, all-in-one chemical regimen that eliminates guesswork. It is not suitable for pools that are not covered, as UV rays from open sunlight will quickly degrade the active ingredients.

Pool Cover Pump – Wayne WAPC250 Cover Pump

Rainwater and melting snow quickly accumulate on top of a solid winter pool cover, creating a heavy pool of water that can stress the cover seams and pull the cover into the pool. This stagnant surface water also attracts breeding insects and collects rotting debris. A reliable cover pump automatically removes this standing water, protecting the cover from tearing and keeping the pool secure.

The Wayne WAPC250 Cover Pump is a top-tier choice because of its intelligent, fully automatic operation. Its iSENSE technology senses water depth and turns the pump on when water reaches 2.1 inches, then shuts it off once the cover is dry. Built with a freeze-protection sensor, the pump will not run if the water is frozen, preventing motor burnout and ensuring long-term reliability.

This pump is capable of moving up to 3,000 gallons per hour, clearing heavy rainfall in minutes. It features a heavy, stable base that resists tipping over on uneven cover surfaces and a check valve that prevents water from flowing back onto the cover once the pump cycles off. To maintain peak performance, the intake screen must be kept clear of wet leaves and pine needles that can choke the impeller.

This pump is essential for anyone using a solid winter cover, especially in regions with heavy winter rainfall or rapid snowmelt. It is not needed for mesh safety covers, which allow rainwater to drain directly into the pool.

Winter Expansion Plug – Hayward SP1022C Plug

Once water is blown out of the pool’s plumbing lines, those lines must be sealed airtight to prevent water from seeping back in and freezing. Winter expansion plugs are inserted into return lines and cleaner ports to create a watertight seal. Without these plugs, water will naturally re-enter the pipes, freeze, and crack the underground PVC.

The Hayward SP1022C Plug is a reliable choice for sealing 1.5-inch threaded return fittings. Made of durable, corrosion-resistant plastic with a high-quality heavy-duty rubber O-ring, it provides a reliable seal that resists chemical degradation. Its threaded design ensures a mechanical, positive lock that will not blow out under the pressure of expanding ice or air pockets.

Fitting selection is critical for success: * Thread size: Standard 1.5-inch MIP (Male Iron Pipe) threads * Material: High-impact ABS plastic * Requirement: Requires Teflon tape or silicone lubricant on the threads to ensure an airtight seal

Before screwing in the Hayward plug, ensure that the threads inside the pool return fitting are clean and free of algae or grit, which can cause cross-threading or allow air leaks.

This plug is the correct choice for in-ground and above-ground pools with standard 1.5-inch threaded return ports. It is not suitable for unthreaded pipe openings, which require rubber compression plugs with wing nuts instead.

Skimmer Guard – Gizzmo Ultra Skimmer Protector

The skimmer is one of the most vulnerable parts of a pool during the winter. Because it sits at the water line, any water that enters the skimmer throat can freeze, expand, and crack the plastic skimmer well. A skimmer guard absorbs this expansion pressure, acting as a sacrificial cushion that collapses inward so the skimmer wall does not crack.

The Gizzmo Ultra Skimmer Protector is uniquely engineered to solve this exact problem while simultaneously sealing the skimmer line. It features a heavy-duty plastic expansion chamber that compresses under ice pressure, diverting force away from the delicate skimmer housing. The Gizzmo Ultra also includes a 1.5-inch and 2-inch dual-thread design at its base, allowing it to screw directly into the bottom of the skimmer port to keep water out of the plumbing.

When installing the Gizzmo, it is highly recommended to wrap the threads with Teflon tape to ensure a watertight seal. Ensure the skimmer lid is placed back on top to prevent heavy snow from packing inside the Gizzmo’s open top. If your pool has a deep skimmer well, make sure to purchase the correct length (standard vs. super) to ensure it reaches the bottom threads while still extending above the water line.

This protector is a must-have for in-ground pool owners in freezing climates who want to secure both their skimmer housing and plumbing in one step. It is not meant for above-ground pool skimmers that are completely drained and disconnected for the winter.

Pool Antifreeze – Splash RV & Marine Antifreeze

Even after blowing out the plumbing lines, small pockets of water can pool in low-lying elbows or sagging underground pipes. Pool antifreeze is added to these lines to lower the freezing point of any residual water, preventing it from expanding and cracking the PVC. This provides a critical safety net against incomplete line blowouts.

Splash RV & Marine Antifreeze is the ideal formula because it is non-toxic and biodegradable, utilizing a propylene glycol base rather than toxic ethylene glycol. It provides freeze protection down to -50 degrees Fahrenheit, ensuring that even extreme winter weather cannot damage underground plumbing. Because it is non-toxic, it is completely safe for pool finishes and will not harm swimmers when the lines are flushed back into the pool in the spring.

When using this product, consider the following: * Formula: 100% propylene glycol-based (never use automotive antifreeze) * Application: Pour directly into plumbing lines using a funnel after blowing them out * Ratio: Use one gallon of antifreeze for every 10 to 15 feet of 1.5-inch pipe

Never dilute the antifreeze with water before pouring, as this raises its freezing point and compromises its ability to protect the pipes from extreme cold.

This antifreeze is essential for in-ground pool owners in climates with deep ground-freezing cycles. It is not designed for use in pool heaters, filtration tanks, or chlorinating systems, which should be drained completely instead.

Cover Water Bags – Swimline Double Water Tubes

For in-ground pools without safety cover anchors, water bags are the industry standard for holding a solid winter cover in place. They lie flat along the pool deck, securing the cover’s edges to prevent high winds from lifting the cover and blowing dirt or leaves underneath. Their flat design prevents them from rolling, ensuring they stay exactly where they are placed throughout the winter.

The Swimline Double Water Tubes are constructed from heavy-gauge, UV-resistant vinyl designed to withstand prolonged exposure to winter sun and freezing temperatures. The double-chamber design provides a major advantage over single tubes: if one chamber punctures or leaks, the second chamber remains filled to keep the cover securely weighed down. They feature leak-proof valves that are easy to fill with a standard garden hose.

When filling water tubes, only fill them to 60% or 75% capacity. Leaving empty space allows the water inside to expand as it freezes without splitting the vinyl seams. Space the tubes end-to-end around the entire perimeter of the pool; leaving gaps invites the wind to get under the cover, which can pull the entire tarp into the pool.

These water bags are perfect for in-ground pool owners using standard solid tarp covers. They are not suitable for above-ground pools, which use cable and winch systems, or for pools equipped with anchored safety covers.

Line Blowout Pump – Cyclone Pro Pipe Blower

Clearing water from underground plumbing lines is the most critical step in preventing catastrophic pipe damage during freezing weather. A line blowout pump forces a high volume of air through the plumbing, pushing all standing water out of the lines and back into the pool. This air-purging process ensures that the pipes remain empty and safe from expansion forces.

The Cyclone Pro Pipe Blower is the preferred choice of pool professionals and serious DIYers due to its powerful, commercial-grade bypass motor. It produces a massive volume of air at 3.0 horsepower, generating the high CFM (cubic feet per minute) required to push water out of deep main drains and long plumbing runs. The durable plastic housing resists impact and moisture, ensuring it survives the damp, demanding environment of pool winterization.

Operating this blower requires a basic understanding of your pool’s plumbing manifold: * Motor: 3.0 HP, 120-volt bypass motor * Hose: Heavy-duty flexible hose with quick-disconnect fittings * Compatibility: Works on standard 1.5-inch and 2-inch PVC plumbing systems

It is critical to connect the blower to the pump basket or skimmer line with a secure, airtight adapter; any air leaks at the connection point will drastically reduce the blower’s effectiveness.

This blower is ideal for in-ground pool owners who want to confidently blow out their own lines without hiring expensive pool service companies year after year. It is overkill for small above-ground pools with short, flexible hoses that can easily be disconnected and stored indoors.

How to Clear Plumbing Lines to Prevent Pipe Damage

Clearing the plumbing lines requires a systematic approach to ensure no water is trapped in low points. Start by lowering the pool water level below the skimmer mouth, then remove all drain plugs from the pump, filter, and heater. Hook up the Cyclone Pro blower to the pump basket, close all valves except for one return line, and turn on the blower.

Watch the open return line in the pool; it will bubble violently as water is pushed out, followed by a continuous mist of air. Once only air is escaping, screw in the Hayward expansion plug tightly to seal the line while the blower is still running to maintain positive pressure. Repeat this exact process for each return line and cleaner line, closing them off one by one.

The final and most critical step is clearing the main drain at the bottom of the pool. Switch the valves to direct air down to the main drain until giant bubbles erupt at the surface of the pool. Quickly close the main drain valve at the equipment pad to lock the air column in the pipe, creating a natural air lock that prevents water from rising back up into the plumbing.

Monitoring Your Covered Pool Throughout the Winter

Winterizing a pool is not a set-it-and-forget-it task. Throughout the cold season, regularly inspect the cover to ensure it remains taut and free of heavy debris accumulation. Heavy piles of wet leaves or branches can abrade the cover material, while excessive weight can pull the water bags or cables loose, exposing the water beneath.

Keep a close eye on the water level underneath the cover. A sudden drop in the pool’s water level can indicate a slow leak in the liner or concrete shell, which can cause the cover to collapse inward under the weight of snow. If the water level drops too low, the cover will lose its support from below, leading to severe structural tension on the pool walls or coping.

Finally, perform a brief chemical check during any mid-winter thaws. If the air temperature rises above 50 degrees Fahrenheit for several days, peel back a corner of the cover and check the chlorine level. Adding a quick dose of liquid chlorine or winter algaecide during a warm spell prevents early spring algae blooms, ensuring a clean, easy pool opening when warm weather returns.

Conclusion

Taking the time to close your pool with high-quality winterization gear is the ultimate insurance policy for your backyard investment. By sealing the plumbing, balancing the chemistry, and securing a heavy-duty cover, you protect your pool from the harshest winter elements. When spring arrives, you will reap the rewards of your diligence with crystal-clear water and equipment that is ready to run.