8 Essential Products to Winterize an Inground Pool

As autumn leaves begin to fall and the summer heat fades into memory, pool owners face the inevitable task of closing down their backyard oasis. Skipping or rushing through this end-of-season ritual can turn your pristine swimming spot into an expensive construction zone come spring. Equipping yourself with the right tools and knowledge is the only way to shield your plumbing, shell, and equipment from the destructive power of freezing winter weather.

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Why Proper Winterization Saves Your Pool Shell and Pipes

Water is one of the few substances on earth that expands when it transitions from liquid to solid, exerting up to 15,000 pounds of pressure per square inch. In an inground pool, this expansion occurs within rigid PVC plumbing lines buried deep underground and against the solid walls of the pool shell. Without room to flex, water-filled pipes will split, and concrete, gunite, or vinyl structures will crack, leading to catastrophic leaks that are incredibly costly to excavate and repair.

Proper winterization creates a defensive buffer zone by removing water from vulnerable areas, adding expansion-absorbing devices, and chemically stabilizing the remaining water. This process prevents structural shifting and stops algae from colonizing the dark, stagnant water under the cover over the long winter months. Taking the time to winterize correctly ensures that opening the pool in May is a simple weekend project rather than a multi-thousand-dollar renovation nightmare.

Steps to Take Before You Add Any Winterizing Chemicals

Preparing your pool for winter starts long before you open any chemical bottles or drag out the cover. You must begin by thoroughly brushing the walls and vacuuming the floor to remove every trace of organic debris, leaves, and silt. Any organic matter left behind will decompose over the winter, consuming your protective chemicals and leaving stubborn stains on your plaster or vinyl liner.

Next, test and balance the pool water to precise parameters: pH between 7.2 and 7.6, alkalinity between 80 and 120 ppm, and calcium hardness between 200 and 400 ppm. Water that is out of balance during the winter becomes highly corrosive or scaling, slowly eating away at underwater light fixtures, plaster, and metal components over months of stagnation.

Finally, lower the water level below the skimmer mouth and return jets, typically about 3 to 18 inches depending on the type of pool cover you use. For vinyl-lined pools with safety covers, the level should remain higher to support the liner, whereas concrete pools can be dropped lower to ensure no water enters the tile line. This step isolates the filtration system and plumbing, setting the stage for a dry, safe blowout of the underground lines.

Winter Cover – Loop-Loc Safety Pool Cover

A high-quality winter cover is your pool’s primary line of defense against heavy snow loads, falling branches, and organic debris. Unlike cheap tarps held down by water bags, a safety cover stretches taut across the pool, anchored securely into the surrounding deck to act as an impenetrable barrier. This prevents leaves from transforming your pool water into a black, smelly tea while providing a crucial safety net for children and pets.

The Loop-Loc Safety Pool Cover is the industry standard for durability, famously demonstrated by their advertisements showing an elephant standing on the taut mesh. It features super-strong, double-webbing polypropylene mesh that allows water to drain through while filtering out even fine debris, preventing dangerous puddles from forming on top. The brass anchors sit flush with your deck when not in use, preserving your backyard’s aesthetic and keeping the deck safe for bare feet in the summer.

Installing this cover requires some initial effort, as you must drill anchor holes into concrete, stone, or wood decking using a rotary hammer drill. Precision is critical; inaccurate measurements during the initial installation will result in sagging, uneven tension, and premature wear on the straps.

• Material: High-grade, UV-stabilized polypropylene mesh
• Weight Capacity: Engineered to support weight up to 4,000 lbs
• Deck Requirement: Requires at least 3 feet of concrete, pavers, or wood decking for anchor installation
• Best For: Households with children, pets, or high wind and snow exposure

This cover is perfect for inground pool owners seeking long-term peace of mind, debris prevention, and structural safety. It is not suitable for pools without a solid surrounding deck to hold the anchors, nor is it ideal for those looking for a cheap, temporary single-season solution.

Winterizing Kit – In The Swim Deluxe Pool Winter Kit

Chemical preparation is what prevents your pool from turning into a swampy, green soup by the time spring rolls around. A dedicated winterizing kit provides pre-measured chemical treatments designed to work in cold, stagnant water over several months. These formulas slow down algae growth, prevent mineral staining, and keep the water clear so that your spring startup is as painless as possible.

The In The Swim Deluxe Pool Winter Kit bundles everything you need into one convenient, cost-effective package. It includes a slow-dissolving non-chlorine winter oxidizer, a powerful winterizer algaecide, a metal-free stain prevention treatment, and a patented winter floating sanitizer dispenser that continuously sanitizes the water. This combination ensures that the active ingredients do not dissipate in the first few weeks of winter, keeping the water protected even during unseasonably warm late-autumn days.

When choosing your kit, you must match the kit size to your pool’s total gallon capacity, rounding up if your pool sits near the limit. It is critical to distribute these chemicals evenly throughout the pool and run the filtration system for at least four hours before lowering the water level to ensure complete mixing.

• Sizing Options: Available for pools up to 10,000, 15,000, and 35,000 gallons
• Included Components: Winterizer, Winter Stain Preventer, Chlorine-Free Shock, and a non-floating winter chemical dispenser
• Chemical Type: Compatible with plaster, vinyl, and fiberglass pools

This kit is ideal for backyard owners who want a straightforward, pre-measured chemical regimen without the guesswork of buying separate components. It is not recommended for pools with existing heavy algae infestations, which must be fully resolved with chlorine shock and scrubbing before the winter kit is applied.

Pool Air Pillow – Robelle Ice Equalizer Pillow

When rainwater and snow collect on top of a solid winter cover, they freeze into a massive, heavy sheet of ice. As this ice expands outward, it exerts immense lateral pressure against your pool walls, risking structural cracking and liner damage. An air pillow sits in the center of the water beneath the cover, acting as a sacrificial pressure absorber that compresses when ice expands inward.

The Robelle Ice Equalizer Pillow is manufactured from heavy-duty, 16-gauge vinyl designed to withstand the crushing forces of freezing winter ice. Unlike flimsy beach-ball-style pillows that pop under the first freeze, this model features reinforced heat-sealed seams and a reliable leak-proof valve that holds air all winter long. It also helps channel rainwater toward the edges of the pool, making it easier for your cover pump to clear the water accumulation.

A common mistake is inflating the air pillow to 100% capacity; it should only be filled to 60% to 70% capacity to allow room for compression when the ice closes in. You must also tie the pillow securely to opposite sides of the pool using durable nylon rope to keep it perfectly centered before pulling the cover over.

• Size Options: 4′ x 4′, 4′ x 8′, and 4′ x 15′ options
• Material: Heavy-duty, UV-resistant 16-gauge vinyl
• Inflation Limit: 60-70% maximum inflation for expansion absorption
• Attachment Points: Four reinforced corner eyelets for centering ropes

This product is an absolute necessity for pool owners using solid winter covers or leaf nets in cold climates. It is less critical for those using tightly tensioned mesh safety covers, though it can still be used to prevent the center of a mesh cover from dipping too far into the pool water under heavy snow.

Skimmer Guard – Ultra Gizzmo Expansion Plug

The pool skimmer is one of the most vulnerable and expensive components of your pool’s plumbing system. Because it sits at the water line, any water that enters the skimmer throat will freeze, expand, and easily crack the thin plastic housing. A skimmer guard inserts into the skimmer well, absorbing this freeze expansion and sealing the plumbing line below from incoming water.

The Ultra Gizzmo Expansion Plug is a heavy-duty, blow-molded plastic tube designed to absorb the crushing pressure of freezing water in the skimmer. This specific model features a built-in 1.5-inch or 2-inch threaded connection at the bottom, allowing it to screw directly into the skimmer’s plumbing port to create a watertight seal. Its hollow, flexible core collapses under ice pressure, saving the surrounding skimmer walls from cracking.

Before purchasing, you must verify whether your skimmer plumbing port requires 1.5-inch or 2-inch threads, as a mismatch will prevent a proper seal. Wrap the threads with Teflon tape before screwing it in to guarantee an airtight and watertight connection during the blowout process.

• Thread Sizes: Available in 1.5-inch and 2-inch male pipe threads
• Length: 16 inches for deep skimmer wells
• Material: Heavy-duty, high-density polyethylene (HDPE)
• Application: Inground pool skimmers

The Ultra Gizzmo is a must-have for inground pool owners living in areas where winter temperatures drop below freezing. It is not suitable for above-ground pool skimmers, which typically require a different, non-threaded style of winter faceplate or guard.

Expansion Plug – Anderson Winterizing Expansion Plug

Once the plumbing lines are blown clear of water, you must seal them off to prevent water from seeping back into the pipes. Expansion plugs insert into the return jets, main drain lines, and cleaner lines, expanding to create a tight, hermetic seal inside the pipe. This prevents the cycle of melting snow and rain from re-entering the plumbing system and causing freeze damage.

Anderson Winterizing Expansion Plugs are the gold standard for pool professionals due to their industrial-grade construction. They feature non-corrosive nylon wing nuts, stainless steel bolts, and thick, marine-grade natural rubber rings that resist chemical degradation and extreme cold. Unlike cheap plastic plugs that crack under tension or slide out of the pipe under pressure, these plugs grip the interior pipe wall firmly and seal completely.

Sizing is critical when selecting expansion plugs, as even a fraction of an inch off can cause a plug to slip or leak. Most standard inground pool return lines require a size #8 (1.5-inch) or size #9 plug, but it is highly recommended to measure the inner diameter of your fittings before purchasing.

• Materials: Marine-grade rubber, stainless steel hardware, nylon wing nuts
• Common Sizes: #8 (for 1.5-inch pipes), #9, #10, and double-plug configurations
• Temperature Range: Engineered to remain flexible down to -40°F
• Use Cases: Return jets, cleaner lines, and skimmer bottoms

These plugs are essential for any inground pool owner performing a winter blowout. They are not suitable for damaged or severely out-of-round fittings, which may require specialized tapered plugs or threaded adapter plugs to achieve a proper seal.

Pool Antifreeze – Splash Non-Toxic Pool Antifreeze

Even with a powerful line blower, removing 100% of the water from underground plumbing lines can be extremely difficult, especially in saggy pipes or deep main drain lines. Pool antifreeze provides an insurance policy by lowering the freezing point of any residual water left in the system, preventing it from expanding and cracking the pipes. It is poured directly into the skimmer, return lines, and equipment lines after they have been blown out and plugged.

Splash Non-Toxic Pool Antifreeze is formulated specifically for recreational water systems, utilizing a propylene glycol base that is completely non-toxic to humans, pets, and local wildlife. It provides burst protection down to -50°F (-45°C), ensuring that even during extreme polar vortex events, your pipes remain safe. Unlike automotive antifreeze, which contains highly toxic ethylene glycol, this formula is safe to discharge back into the pool when priming the system in the spring.

Never dilute pool antifreeze with water before pouring it into your lines, as this drastically raises its freezing point and reduces its protective capabilities. You will typically need one to two gallons of antifreeze per plumbing line to ensure adequate coverage throughout the system.

• Chemical Base: 100% Propylene Glycol (non-toxic)
• Temperature Rating: Burst protection down to -50°F (-45°C)
• Safe For: PVC, copper, brass, and plastic plumbing systems
• Volume: Sold in 1-gallon bottles

This product is highly recommended for pool owners in northern regions where ground freeze is deep and prolonged. It is not necessary for warm-climate pool owners who only experience light, overnight frosts and do not fully close their pools.

Cover Pump – Little Giant APCP-1700 Cover Pump

Rainwater and melting snow quickly accumulate on solid pool covers, creating a heavy pool of water that strains the cover material and anchors. This standing water not only poses a significant safety hazard but can also seep through cover seams and contaminate the balanced pool water below. A submersible cover pump automatically removes this water, keeping the cover dry, lightweight, and stable throughout the autumn and spring.

The Little Giant APCP-1700 Cover Pump is a workhorse designed specifically for this demanding task. It features an integrated mechanical float switch that automatically turns the pump on when water reaches 2 inches and shuts it off when the surface is clear. With a flow rate of 1,700 gallons per hour, it quickly clears large accumulations of water, while its wide, stable base prevents it from tipping over on the uneven surface of a soft cover.

To prevent the pump from clogging, you must periodically clear leaves and organic debris from the intake screen at the base. Additionally, the pump should be removed from the cover and stored indoors before deep freezing temperatures set in, as ice can damage the pump housing and impeller.

• Flow Rate: 1,700 GPH at a 1-foot lift
• Activation: Automatic (turns on at 2 inches, off at 1.5 inches)
• Power Cord: 25-foot heavy-duty power cord
• Discharge Connection: Standard 3/4-inch garden hose thread

This pump is an indispensable tool for anyone using a solid winter cover or a tarp-and-water-bag setup. It is not required for pool owners with high-tension mesh safety covers, which are designed to allow water to drain naturally straight through the mesh into the pool.

Line Blower – Cyclone Pro Line Bypass Blower

Standard shop vacuums simply lack the power and volume of air required to push water out of deep underground pool plumbing lines, especially the main drain at the bottom of the deep end. A dedicated line blower delivers high-volume, low-pressure air that forces water out of the lines completely, leaving them bone-dry. This is the single most critical step in preventing freeze damage to your underground PVC lines.

The Cyclone Pro Line Bypass Blower is the gold standard for professional pool closers and serious DIYers. Powered by a 3.0 horsepower, dual-stage bypass motor, it generates up to 130 CFM of air volume, which is enough force to blow out lines in pools up to 8 feet deep. Its bypass motor design ensures that even if air backpressure builds up, the motor remains cool and protected from overheating, extending the life of the tool for years.

Operating the Cyclone Pro requires a proper connection to your plumbing system, typically through the skimmer or the pump housing using a heavy-duty, reinforced hose. Because of the extreme air pressure generated, you must ensure all connections are clamped tightly to prevent hoses from whipping loose during operation.

• Motor Power: 3.0 HP dual-stage bypass motor
• Performance: 130 CFM (Cubic Feet per Minute) air flow
• Hose Size: 1.5-inch threaded outlet with quick-connect adapters
• Weight: 14 lbs, lightweight and portable

This tool is perfect for dedicated pool owners who want to winterize their own pools year after year with the confidence of a professional service crew. It is not recommended for casual owners looking for a cheap, one-off solution, as it represents a significant upfront investment.

How to Safely Blow Out and Plug Your Plumbing Lines

Blowing out your plumbing lines requires a systematic approach to ensure no water is trapped in low-lying sections of PVC. Begin by hooking up your line blower to the pump basket inlet or the skimmer line. Turn on the blower and open the valves to the return lines first; you will see a dramatic geyser of water blast out of the pool’s return jets.

To plug the lines safely, you must work while the air is actively blowing to prevent water from re-entering the pipe. As the return jets start blowing pure air, insert your expansion plugs and tighten the wing nuts until they are snug. Once all return lines are plugged, divert the airflow to the main drain at the bottom of the pool until a massive geyser of bubbles erupts in the deep end. Quickly close the main drain valve at the equipment pad to air-lock the line, keeping the water level pushed down deep below the frost line.

Finally, clear the skimmer lines by blowing air from the pump back toward the skimmer mouth. Once the water is completely evacuated from the skimmer well, quickly screw in your Gizzmo or expansion plug to seal the port. Pour a generous amount of non-toxic pool antifreeze into the skimmer body and any remaining equipment pipes to complete the process.

Crucial Off-Season Checks to Prevent Mid-Winter Damage

Winterizing your pool is not a “set-it-and-forget-it” task that ends in October. Throughout the winter, freezing temperatures, heavy snow accumulation, and shifting ground can compromise your winter prep. Performing regular visual inspections every few weeks is the key to catching minor issues before they escalate into structural damage.

First, check the tension on your safety cover springs; they should be compressed about halfway to keep the cover taut and prevent sagging under snow loads. If you notice the center of the cover dipping into the water, use a long-reach pool brush to clear off excessive snow or leaf accumulation, and verify that the pool’s water level hasn’t dropped due to a hidden leak. A significant drop in the pool’s water level removes crucial support from beneath a safety cover, putting extreme stress on the brass anchors and deck.

Additionally, inspect your equipment pad to ensure that rodents haven’t nested inside the heater or pump housing, where they can chew through electrical wiring. Check that your skimmer guards and expansion plugs remain tightly in place, as freeze-thaw cycles can sometimes shift or loosen plastic components. Spending just ten minutes conducting these simple checks during the off-season will protect your investment and guarantee a smooth spring opening.

Conclusion

Taking the time to properly winterize your inground pool with the right gear is the ultimate investment in your property’s longevity and your own peace of mind. By systematically blowing out your lines, chemically balancing your water, and shielding your pool with durable covers and plugs, you protect your backyard oasis from the worst winter can throw at it. When the warm spring sun finally returns, you will reap the rewards of your diligence with a crystal-clear pool that is ready for another season of fun.