How to Close Your Pool: 7 Steps for a Safe Winter

Why Proper Pool Closing Protects Your Investment All Winter

Pool closing done right is the single most important thing you can do to protect your backyard investment before winter hits.

Here’s a quick overview of the essential steps:

1. Time it right — Close when water temperature is consistently below 65°F
2. Balance your water chemistry — Target pH 7.2–7.8, Alkalinity 80–120 ppm, Calcium Hardness 175–225 ppm
3. Shock the pool — The night before closing, raise Free Chlorine to 3–5 ppm
4. Add algaecide — The morning after shocking, once chlorine drops below 5 ppm
5. Lower the water level — 12–18 inches below the skimmer for mesh covers; 3–6 inches for solid covers
6. Blow out and plug the plumbing lines — To prevent frozen, cracked pipes
7. Install your winter cover — Secured tightly with no slack or tenting

Skipping even one of these steps can mean a nasty surprise in spring. Frozen plumbing alone can cost $500–$2,000 to repair.

The good news? Most homeowners can complete the full process in 2–4 hours. And a well-closed pool actually saves money — a proper cover can cut your off-season chemical and electrical costs by at least 50%.

Whether this is your first time winterizing or you just want to make sure you’re doing it right, this guide walks you through every step clearly and simply.

The Ultimate Step-by-Step Guide to Pool Closing

Closing up the backyard pool is always a bit bittersweet. It marks the official end of summer pool parties, late-night swims, and floating lazily under the warm sun. However, taking the time to properly execute your pool closing routine ensures that when May 2027 rolls around, your pool will be ready to open with minimal hassle.

To help you stay organized, we have compiled an essential winterizing checklist. By following these structured steps, you protect your expensive filtration equipment, preserve your pool shell, and keep your family safe throughout the freezing winter months. For those who want professional peace of mind, you can find More info about closing services to make the process completely hands-free.

Timing Your Pool Closing: When is the Best Time?

One of the most common mistakes pool owners make is closing their pools too early in the season. It is tempting to wrap up the pool right after Labor Day when the kids head back to school, but patience is a virtue here.

The golden rule of pool closing is to wait until the water temperature is consistently below 65°F (approximately 18°C). Why? Algae thrives in warm water. If you close your pool when the water is still warm, your winterizing sanitizer will deplete rapidly, leaving the pool vulnerable to massive algae blooms. By waiting for the autumn leaves to fall and the water to cool, you naturally prevent algae growth and ensure the water stays clear under the cover. To learn more about the historical significance of pool closing dates, check out More info about National Pool Closing Day.

Balancing Water Chemistry and Winter Chemicals

Before you put the cover on, you must ensure your water chemistry is perfectly balanced. Unbalanced water during the winter can scale your pool walls, corrode metal fixtures, or ruin your pool liner. Ideally, you should test and balance your water 24 hours to a week before you plan to close.

Aim for these target chemical levels:

• pH levels: 7.2 to 7.8
• Total alkalinity: 80 to 120 ppm
• Calcium hardness: 175 to 225 ppm (up to 400 ppm for plaster pools)

If you need to raise both alkalinity and pH simultaneously, using household baking soda is a highly effective and budget-friendly trick.

Once your water is balanced, it is time for the chemical sequencing rule. This is where many DIYers make mistakes. You must shock the pool with chlorine first to raise your Free Chlorine levels to 3–5 ppm. Do this the night before closing so the sun’s UV rays do not degrade the chlorine.

The following morning, once your free chlorine drops below 5 ppm, add a high-quality, long-lasting winter algaecide, such as polyquat 60. Never mix chlorine shock and algaecide at the same time; chlorine is so strong that it will destroy the algaecide on contact, rendering it completely useless. For a deeper look at how cold weather impacts your pool, read More info about winter pool water.

Winterizing Pool Plumbing and Equipment

In freezing climates like Northeastern Pennsylvania, winterizing your pool plumbing is the most critical step of the entire process. Water expands when it freezes, which can easily shatter plastic skimmer throats and crack underground pipes.

First, deep clean your filtration system. Backwash sand or DE filters. If you have a cartridge filter, remove the cartridges and soak them in a specialized filter cleaner. Once clean, store them in a dry, non-freezing location.

Next, remove the drain plugs from your pump, filter tank, heater, and chlorinator. A classic pro-tip is to store all these small plastic drain plugs inside the pump’s strainer basket so you do not lose them over the winter.

Now, lower the water level. The depth depends on your cover:

• For mesh covers, lower the water 12 to 18 inches below the skimmer.
• For solid covers, lower the water 3 to 6 inches below the skimmer.

Once lowered, perform a line blowout. Use a high-volume air compressor or a shop vac on the blow setting to force all water out of the skimmers, return lines, and main drain. Once you see air bubbling out, seal the lines tightly with expansion plugs. For added safety, pour a half-gallon to a full gallon of non-toxic, pool-grade antifreeze down each line. Never use automotive antifreeze, as it is highly toxic to both humans and pool systems. Finally, thread a Gizzmo expansion plug into your skimmer to absorb ice expansion pressure and protect the skimmer walls.

For more detailed safety tips, explore More info about preventing freeze damage and check out the Winterizing a Pool: Step-by-Step Closing Guide.

Choosing and Installing the Right Pool Cover

Your winter pool cover is your pool’s shield against the elements. Choosing the right one depends on your budget, safety concerns, and aesthetic preferences:

• Mesh Safety Covers: These are anchored securely into your deck. They allow rain and snowmelt to drain through while blocking leaves and debris. Because water passes through, you must lower your pool water further (12-18 inches) to accommodate winter accumulation.
• Solid Safety Covers: These also anchor into the deck but block all water and light. This keeps your pool water pristine, but you will need a cover pump to remove standing water from the top of the cover.
• Solid Tarp Covers: A budget-friendly option held down by water bags. Never use bricks or cinder blocks to weigh down a tarp cover, as they can slip in and ruin your pool liner.
• Automatic Covers: If you use an automatic pool cover for the winter, do not lower your water level. Automatic covers rely on the water’s surface tension to support heavy snow loads. Lowering the water can cause the cover tracks to warp or snap under the weight of winter snow.

Whichever cover you choose, ensure there is zero slack. “Tenting” or loose edges can cause the cover to rip under wind or snow pressure. For more guidance on selecting the perfect cover, see More info about pool covers.

DIY vs. Professional Service: Costs, Mistakes, and Above-Ground Differences

Properly winterizing your pool is the best way to safeguard your backyard investment. But should you tackle this multi-hour project yourself, or is it better to call in the professionals? To help you decide, let’s look at the differences between pool types, costs, and common pitfalls. To understand the science behind why we go through this process every autumn, read More info about why we close pools.

Above-Ground vs. In-Ground Pool Closing Differences

Closing an above-ground pool requires a slightly different approach than an in-ground pool. Because above-ground pools sit entirely above the frost line, they are highly vulnerable to structural damage from expanding ice.

Here is a quick comparison of the two processes:

Feature / Step	Above-Ground Pools	In-Ground Pools
Plumbing Prep	Disconnect and drain all flexible hoses entirely. Store pump/filter indoors.	Blow out underground lines with an air compressor and seal with expansion plugs.
Ice Protection	Must use an inflated air pillow (pool pillow) in the center under the cover.	Use Gizzmos in skimmers and antifreeze in plumbing lines.
Cover Securing	Secure with a cable and winch system tightened around the pool perimeter.	Secure with brass deck anchors (safety cover) or water bags (tarp cover).
Water Level	Lower below the skimmer and return inlet, but never drain completely.	Lower 3 to 18 inches depending on the type of cover used.

The use of an air pillow is absolutely vital for above-ground pools. It acts as an ice compensator. When the water freezes, it expands inward against the pillow rather than outward against the pool walls, preventing the structure from collapsing. For a detailed walkthrough, view More info about above-ground pool winterization.

DIY vs. Professional Service: Costs and Common Mistakes

If you choose the DIY route, your pool closing costs will generally range from $50 to $150 for chemicals, plugs, and antifreeze. On the other hand, hiring a professional service team typically ranges from $150 to $400 depending on your pool size, cover type, and location.

While DIY is highly cost-effective, the risks are substantial if you lack the proper equipment. The most common DIY mistake is failing to complete a proper plumbing blowout. If even a small amount of water remains in your underground pipes, a hard freeze can crack those lines, resulting in a spring repair bill between $500 and $2,000.

Other common mistakes include:

• Adding shock and algaecide at the same time (which neutralizes the algaecide).
• Using bricks, wood, or concrete blocks to hold down tarp covers.
• Closing the pool while the water temperature is still above 65°F.
• Forgetting to turn off pool timers and circuit breakers after closing.

If you live in Northeastern Pennsylvania—including Wilkes-Barre, Scranton, Dickson City, Bartonsville, Doylestown, Tannersville, Bloomsburg, Allentown, Beach Lake, or Lake Wallenpaupack—the team at Aqua Leisure Pools and Spas is here to help. They can handle the entire winterization process for you, ensuring your lines are blown out professionally and your pool is completely protected from harsh winter freezes. To learn more about what to watch out for, read More info about common winterizing mistakes.

Posted by chris@enx2marketing.com in Pools