9 Essential Supplies for Winterizing an Inground Pool Step by Step

Watching the autumn leaves start to fall means the swim season is drawing to a close, but the work of protecting your backyard investment is just beginning. Failing to prepare an inground pool for freezing temperatures can lead to catastrophic pipe failures, cracked concrete, and ruined filtration systems that cost thousands to repair. Securing the right seasonal supplies now ensures that when spring finally rolls around, reopening the pool is a seamless, stress-free celebration rather than an expensive recovery mission.

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Why Winterizing Your Inground Pool Matters

Water expands by nearly nine percent when it freezes, exerting immense pressure on whatever container holds it. In an inground pool, this expansion happens inside underground PVC plumbing lines, delicate filtration valves, and the concrete or vinyl shell itself. If water is left to freeze unchecked in these components, it can crack pipes buried deep underground, leading to devastating leaks that require costly excavation to fix.

Beyond mechanical protection, proper winterization preserves water chemistry and structural surfaces during months of dormancy. Allowing algae, organic debris, and acidic rain to sit untreated for six months will ruin pool plaster, stain vinyl liners, and create a swampy mess that takes weeks of expensive chemical treatment to clear in the spring. Investing a weekend in thorough winter preparation saves both your wallet and your sanity.

Winter Chemical Kit – In The Swim Ultimate Kit

Over the long winter months, stagnant pool water becomes a breeding ground for algae and staining minerals if left untreated. A comprehensive winter chemical kit slowly releases sanitizing and protecting agents into the water, preventing unsightly scaling and keeping the pool clean until spring. Without these specialized, slow-dissolving chemicals, pool owners face a green, murky nightmare come May.

The In The Swim Ultimate Kit stands out because it provides a pre-measured, multi-stage defense system tailored specifically for cold-weather dormancy. It includes a powerful winterizer shock, a slow-releasing winter stain away formula, a non-chlorine winter oxidizer, and a unique patented winterizing chemical dispenser that floats beneath the cover to continuously sanitize. This targeted combination ensures your pool finishes the winter in the same pristine state it started.

These kits are sized based on total pool gallonage, typically ranging from 10,000 up to 35,000 gallons. Always buy a kit rated slightly higher than your actual pool capacity to ensure complete chemical coverage, especially if your winter season stretches longer than five months. Remember to run the pool filter for at least four to six hours after adding these chemicals to distribute them thoroughly before lowering the water level.

• Available sizes: Up to 10,000, 22,000, and 35,000 gallons
• Includes: Winterizer, Winter Stain Away, Non-Chlorine Shock, and floating sanitizer dispenser
• Compatibility: Safe for vinyl, fiberglass, and plaster inground pools

This kit is perfect for pool owners who want an all-in-one chemical solution without the hassle of measuring individual bulk products. It is not suitable for those looking to patch together leftover summer chemicals, which lack the cold-temperature stability required for winter-long protection.

Line Blower – Cyclone Pro Line Bypass Blower

Getting every drop of water out of underground plumbing lines is the single most critical step in preventing freeze damage. A dedicated line blower uses high-volume, low-pressure air to push water completely out of the main drains, skimmers, and return lines. Standard shop vacs simply lack the power and volume required to clear deep subterranean pipes effectively, leaving water trapped in low points to freeze.

The Cyclone Pro Line Bypass Blower is the gold standard for pool owners and service pros alike due to its rugged 3.0 horsepower motor and dual-stage bypass design. This bypass configuration protects the motor from overheating when backpressure builds up during the blow-out process, a common failure point for cheaper utility vacuums. Its durable plastic housing resists denting and rust, making it a reliable tool for decades of seasonal use.

Using this tool requires a heavy-duty, outdoor-rated extension cord to handle the high amperage draw without tripping breakers. Connecting the blower to the plumbing system requires a standard 1.5-inch threaded hose adapter, which must be secured tightly to avoid air leaks. The learning curve is moderate, but taking the time to understand the sequence of opening and closing valves pays off immediately.

• Motor: 3.0 HP, 120-volt dual-stage bypass motor
• Airflow: 130 CFM (Cubic Feet per Minute)
• Port size: 2.0-inch inlet and outlet connections

This blower is ideal for pool owners committed to doing their own winterization year after year, saving hundreds of dollars in professional service fees. It is not necessary for pool owners in mild climates where hard freezes do not occur and lines do not require clearing.

Winter Expansion Plugs – Blue Devil Rubber Plugs

Once the water has been blown out of the pool return lines, those lines must be sealed immediately to prevent water from seeping back in. Winter expansion plugs act as watertight corks, sealing off the open pipe ends inside the pool wall. Without these plugs, the rising winter water level from rain and melted snow would re-enter the plumbing and cause freeze damage.

Blue Devil Rubber Plugs are designed with a heavy-duty, tapered rubber body that compresses tightly when the integrated wing nut is tightened. Unlike cheap plastic alternatives that crack in sub-zero temperatures, these plugs use high-grade, freeze-resistant rubber and corrosion-resistant stainless steel bolts and nuts. They create a reliable, airtight seal that resists the shifting pressures of ice.

Standard pool returns typically require size #8, #9, or #10 plugs, but it is critical to measure the inner diameter of your specific fittings before ordering. Over-tightening the wing nuts can crack old plastic return fittings, so turn them until they are snug and the rubber bulges slightly. Always keep a few extra plugs on hand in various sizes to account for unexpected plumbing configurations or misplaced parts.

• Available sizes: #00 through #14 (covering 1/2-inch to 4-inch pipe diameters)
• Material: Heavy-duty rubber with stainless steel hardware
• Application: Return lines, cleaner lines, and skimmer ports

These plugs are a non-negotiable necessity for anyone winterizing an inground pool in a freezing climate. They are not intended for permanent plumbing repairs or high-pressure system testing during the active swim season.

Skimmer Guard – Ultra Gizzmo Expansion Plug

Skimmers are highly vulnerable to freeze damage because water naturally collects in them and freezes from the top down, expanding outward against the delicate plastic walls. A skimmer guard acts as an expansion compensator, absorbing the crushing pressure of freezing water so the skimmer housing does not crack. It also threads directly into the bottom plumbing line to seal the pipe from water entry.

The Ultra Gizzmo Expansion Plug features a robust, hollow plastic tube designed to collapse safely under ice pressure, diverting force away from the skimmer body. It features a sealed top with a blowout valve, allowing pool owners to clear the line with air and seal it without removing the Gizzmo. The high-density polyethylene construction and integrated double-thread design ensure a watertight fit in standard 1.5-inch and 2-inch skimmer threads.

Always apply Teflon tape to the Gizzmo’s threads to guarantee an airtight seal and prevent the plastic threads from binding inside the skimmer over the winter. If your skimmer has a deep throat or custom dimensions, measure the depth to ensure the Gizzmo is tall enough to protrude above the expected winter water line.

• Thread sizes: 1.5-inch and 2-inch dual threads
• Overall length: 16 inches for standard deep skimmers
• Material: High-density polyethylene (HDPE)

This is a must-have tool for inground pool owners with built-in skimmers in regions that experience prolonged hard freezes. It is not suitable for above-ground pool skimmers, which typically require different sizing and support systems.

Pool Antifreeze – Splash Pool & Spa Antifreeze

Even after blowing out pool lines, small pockets of water can migrate back into low spots of the plumbing through condensation or minor seal leaks. Pool antifreeze acts as a critical insurance policy, lowering the freezing point of any remaining liquid so it cannot expand and rupture the pipes. It provides peace of mind when winter temperatures drop into the negatives.

Splash Pool & Spa Antifreeze is formulated specifically for recreational water systems using a non-toxic propylene glycol base. Unlike automotive antifreeze (ethylene glycol), which is highly toxic to pets, humans, and local wildlife, this formula is completely safe for backyard environments and pool chemistry. It protects plumbing lines down to -50 degrees Fahrenheit without damaging PVC, rubber gaskets, or vinyl pool liners.

This product must be poured directly into the plumbing lines after they have been blown out and plugged, usually using a funnel inserted into the skimmer or return lines. Never add pool antifreeze directly to the open pool water, as it will simply dilute and serve no protective purpose for the plumbing. One gallon is typically required for every 10 to 15 feet of underground piping.

• Active ingredient: Non-toxic propylene glycol
• Freeze protection limit: Down to -50°F (-46°C)
• Packaging: 1-gallon bottles

This antifreeze is essential for pool owners in northern climates where winter temperatures consistently drop below freezing for weeks at a time. It is not for automotive use, and it should not be used in pools that are kept open or heated through the winter.

Pool Air Pillow – Robelle Ice Equalizer Pillow

When solid ice forms across the surface of a covered pool, it expands outward, putting tremendous lateral pressure on the pool walls and the cover itself. An air pillow sits in the center of the pool beneath the cover, creating a void that forces the ice to expand inward against the soft pillow rather than outward against the pool structure. It also helps channel rainwater and melting snow toward the edges of the cover for easier removal.

The Robelle Ice Equalizer Pillow is constructed from heavy-duty 16-gauge vinyl, making it exceptionally resistant to punctures from ice edges and heavy snow loads. It features a reliable Push-n-Pull valve that prevents air leaks during extreme temperature shifts. The perimeter eyelets allow you to secure the pillow centrally in the pool using ropes, keeping it from drifting to the edges where it would be useless.

The most common mistake is inflating the pillow to 100 percent capacity; instead, inflate it to about 60 to 70 percent capacity to allow room for compression as the ice expands. If fully inflated, the air pillow will pop under the weight of the first heavy snowfall. Use nylon ropes tied to opposite sides of the pool deck to keep the pillow floating perfectly in the center of the water.

• Available sizes: 4×4 feet, 4×8 feet, and 4×15 feet
• Material: 16-gauge heavy-duty vinyl
• Features: Reinforced corner grommets/eyelets

This pillow is highly recommended for pools using solid vinyl winter covers to prevent cover stress and wall damage. It is less critical for pools utilizing tension-based mesh safety covers, which allow water to pass through.

Safety Cover – Loop-Loc Mesh Safety Pool Cover

A high-quality cover does more than keep leaves and debris out of your pool; it is a critical safety barrier that prevents children, pets, and wild animals from accidentally falling into the freezing water. It also blocks sunlight to suppress algae growth during the spring warming months. A secure cover transforms an open hazard into a clean, safe, and secured backyard space for the winter.

The Loop-Loc Mesh Safety Pool Cover is legendary for its strength, famous for being strong enough to support massive weight without tearing. Constructed from ultra-strong, lightweight polypropylene mesh, it allows rain and melting snow to drain through while blocking fine debris and silt. The heavy-duty stainless steel springs and brass anchors sit flush with your deck when not in use, providing a clean look and unmatched durability.

Safety covers are custom-fit to the exact shape and size of your pool, requiring precise measurements of your deck and coping. Installing a Loop-Loc cover for the first time requires drilling anchor holes into your concrete or wood deck using a rotary hammer drill. Once the initial installation is complete, putting the cover on and taking it off each season takes less than twenty minutes with the included installation tool.

• Material: High-density polypropylene mesh fabric
• Hardware: Corrosive-resistant stainless steel springs and flush brass anchors
• Safety rating: Meets or exceeds ASTM F1346-91 safety standards

This cover is the ultimate choice for pool owners prioritizing safety, longevity, and a clean off-season aesthetic. It is not suitable for those with limited budgets who prefer cheap, disposable tarp-style covers held down by water bags.

Pool Cover Pump – Wayne WAPC250 Automatic Pump

Rainwater, melted snow, and melting ice accumulate quickly on top of solid pool covers, creating heavy, stagnant puddles that strain the cover seams and anchors. If left untreated, this massive weight can drag the cover down into the pool, contaminating the clean pool water below. A dedicated cover pump automatically removes this accumulated surface water, keeping the cover light and functional.

The Wayne WAPC250 Automatic Pump stands out because of its smart iSpout technology, which senses water levels and turns the pump on or off automatically. This means you do not have to venture out into freezing weather to plug it in or monitor its progress. It features a high-flow rate of up to 3,000 gallons per hour and includes an integrated debris guard that prevents leaves from clogging the intake.

The pump must sit upright on the cover, ideally in the deepest pocket of accumulated water, and be connected to a standard garden hose to direct the discharge away from the pool deck. Keep the power cord plugged into a GFCI outlet to ensure electrical safety around water. In areas with extreme freezing temperatures, bring the pump indoors temporarily during deep freezes to prevent ice from damaging its internal impeller.

• Flow rate: Up to 3,000 GPH (Gallons Per Hour)
• Auto-on point: Activates at 2.125 inches of water; turns off at 0.75 inches
• Power: 1/4 HP oil-free motor with a 25-foot power cord

This automatic pump is an essential tool for anyone using a solid vinyl cover or a hybrid cover that accumulates standing water. It is not required for pool owners with porous mesh safety covers that allow water to drain directly into the pool.

Leaf Net Cover – Blue Wave Bronze Leaf Net

If your yard is surrounded by deciduous trees, autumn can bury your winter pool cover in a thick layer of heavy, wet leaves. Removing these sodden leaves in the spring is a grueling, messy chore that often results in decaying organic matter slipping into the clean pool water during cover removal. A leaf net sits on top of your main winter cover, catching falling leaves so they can be peeled off easily in one quick motion.

The Blue Wave Bronze Leaf Net features a durable, woven polyethylene mesh with a tight weave that catches even small leaf fragments while letting water pass through freely. It is designed with an extra 4-foot overlap to ensure complete coverage over the edges of your main winter cover, preventing leaves from blowing underneath. The heavy-duty ratchet and cable system keeps the net securely anchored against high autumn winds.

Install the leaf net immediately after putting your main winter cover on, just as the leaves begin to drop in earnest. Once the trees are completely bare in late autumn, simply gather the edges of the leaf net, drag it off the pool to discard the leaves, and store the net dry for the remainder of the winter. This prevents the leaves from rotting on the cover all winter long.

• Material: UV-protected woven polyethylene
• Overlap: 4 feet beyond the designated pool size
• Includes: Heavy-duty vinyl-coated steel cable and metal winch/ratchet

This net is a lifesaver for pool owners with heavy tree cover who want to avoid the messy chore of scooping wet leaves in the spring. It is not necessary for pool owners in open yards with no surrounding trees or foliage.

How to Blow Out Pool Plumbing Lines Safely

Blowing out pool lines requires a methodical, step-by-step approach to prevent damage to the pipes and ensure no water is left behind. Start by lowering the pool’s water level below the skimmer mouth, typically about four to six inches, using your pool filter’s waste setting or a submersible pump. Next, hook up the line blower to your pool’s plumbing system, usually at the main pump basket or through the skimmer line, making sure all other valves are closed to direct the air pressure exactly where you want it.

Turn on the blower and begin clearing the lines one by one, starting with the return line closest to the pump and working your way to the furthest. You will see water bubble violently out of the return jets inside the pool; once the bubbling stops and only mist or dry air escapes, insert a winter expansion plug tightly into the fitting. Repeat this process for each return jet, the cleaner line, and finally the main drain at the bottom of the pool.

Clearing the main drain requires special care because it is at the deepest part of the pool. Blow air through the main drain line until you see massive air bubbles rising to the pool surface, then quickly close the slide valve at the equipment pad to create an air lock. This air lock uses the trapped air pressure to keep pool water from rising back up the pipe, eliminating the need to plug the main drain underwater.

Storing Your Pool Equipment for the Offseason

Leaving sensitive pool equipment exposed to freezing rain, ice, and snow will drastically shorten its lifespan and lead to costly electrical failures. Once the lines are blown out, remove all drain plugs from your pump, filter tank, heater, and chlorinator to allow any residual water to drain completely out of the equipment. Leaving these plugs in place allows trapped water to freeze, crack pump housings, and destroy expensive copper heater headers.

Store the removed drain plugs, pump baskets, and pressure gauges inside the pump basket or a labeled bag, keeping them in a dry, indoor location so they do not get lost over the winter. If you have a cartridge or diatomaceous earth (DE) filter, remove the elements, hose them down thoroughly to remove oils and debris, and store them indoors where pests cannot chew through the delicate mesh fabric.

Electrical components like salt chlorinator cells, chemical feeders, and pool cleaners should also be disconnected and stored in a temperature-controlled space like a basement or heated garage. For heavy equipment that must remain outdoors, such as heaters and pumps, cover them with a breathable, weather-resistant utility cover to block moisture while preventing mold-inducing condensation build-up.

Conclusion

Taking the time to properly winterize your inground pool with high-quality supplies is the best investment you can make for your backyard retreat. By systematically clearing your plumbing, balancing your water chemistry, and securing a reliable safety cover, you protect your pool from devastating freeze damage and ensure a crystal-clear opening next spring. Step into the cold season with confidence, knowing your pool is fully protected and ready for its winter hibernation.