As the swimming season winds down, are you asking yourself, “What’s the right way to close my pool for the winter?” It’s a critical question, and getting the answer right is more important than you might think. The difference between a simple cover-up and a professional winterization can be thousands of dollars in repairs down the line. Protecting your pool’s plumbing, surfaces, and equipment from impending freezing temperatures is vital for its longevity and for your peace of mind. Whether you’re a DIY pro or just want to understand the process, this guide has the essential information you need for a worry-free off-season.
1. Clean Your Pool Thoroughly
The first step is to get your pool as clean as possible. Closing a dirty pool is a recipe for a green, swampy mess when you open it in the spring. Any leaves, dirt, or algae left in the water will decompose over the winter, staining surfaces and providing food for algae blooms.
- Skim the Surface: Use a leaf net to remove all floating debris like leaves, bugs, and twigs.
- Brush the Walls: Vigorously brush the pool walls, steps, ladders, and any corners to dislodge stubborn dirt and algae spores. This pushes them into the water where the filter and vacuum can remove them.
- Vacuum the Bottom: Thoroughly vacuum the entire pool floor to suck up all the settled debris you just brushed down. Run the main filter while you do this to catch everything. A clean start now will save you a ton of work later.
2. Balance the Water Chemistry
Properly balanced water protects your pool’s surfaces (liner, plaster, fiberglass) from staining, scaling, and etching during the winter months. It also ensures your winterizing chemicals work effectively.
- Test the Water: Use a reliable water testing kit to check the key chemical levels.
- Adjust as Needed: Add balancing chemicals according to the test results to achieve the following ideal winter ranges:
- pH: 7.4−7.6 (Prevents corrosion and scaling)
- Total Alkalinity: 80−120 ppm (parts per million) (Acts as a buffer to keep the pH stable)
- Calcium Hardness: 200−400 ppm (Protects plaster and vinyl surfaces from damage)
Allow the pump to run for several hours after adding chemicals to ensure they are fully dissolved and circulated.
3. Shock the Pool
Shocking the pool is the process of super-chlorinating the water. This is a crucial step to eliminate any lingering bacteria, algae, and other organic contaminants before closing.
- Add Chlorine Shock: Use a granular pool shock, following the manufacturer’s dosage instructions for closing a pool (this is typically a higher dose than a regular weekly shock). It’s best practice to pre-dissolve the shock in a bucket of pool water before carefully pouring it around the perimeter of the pool.
- Run the Filter: After shocking, you must run your filter and pump for a continuous 24-hour cycle. This ensures the shock is completely circulated throughout the entire system, sanitizing every part of your pool.
4. Add Winterizing Chemicals
After the chlorine level from the shock has returned to a normal range (around 1−3 ppm), it’s time to add chemicals specifically designed for closing. These are often sold in convenient “winterizing kits.”
- Winter Algaecide: This is a long-lasting, concentrated algaecide that works in cold water to prevent algae from blooming under the cover.
- Stain & Scale Preventer: This chemical binds to minerals and metals in the water, preventing them from settling on and staining your pool surfaces over the winter.
- Application: With the pump still running, add these chemicals as directed by the product instructions, allowing them to circulate for a few hours.
5. Lower the Water Level
Lowering the water level is critical to prevent freeze-thaw damage to your skimmer and return lines. As water freezes, it expands with incredible force and can easily crack pipes and equipment.
- In-ground Pools: Lower the water level to about 4-6 inches below the bottom of the skimmer opening. This ensures the water is also well below the return jet fittings on the wall.
- Above-ground Pools: For pools with a standard thru-wall skimmer, lower the water to 4-6 inches below the skimmer. If you are disconnecting the hoses and using a skimmer cover plate, you may not need to lower the water as much.
- How to Drain: You can lower the water by setting your multiport filter valve to the “Waste” setting or by using a submersible utility pump.
6. Drain Equipment and Clear Pipes
This is the most important step for preventing costly freeze damage. Every drop of water must be removed from your equipment and plumbing.
- Drain Equipment: Locate and remove the drain plugs from your pump, filter, heater, and any other connected equipment (like a chlorinator). Place the small plugs in the pump’s strainer basket so you don’t lose them over the winter.
- Clear the Lines: You must force all water out of the plumbing lines. The most effective method is to use a powerful shop vacuum or an air compressor set to a low pressure.
- Set the vacuum to its “blower” function.
- Force the air through the skimmer line until you see only air bubbles coming out of the return jets.
- Once a line is clear, firmly screw a winter expansion plug into that return jet fitting to seal it off.
- Repeat for all return lines.
- Finally, screw a “Gizzmo” or a similar skimmer freeze protector into the skimmer. This threaded tube is designed to collapse and absorb ice expansion, saving your skimmer from cracking.
7. Cover the Pool
A good winter cover is your pool’s final line of defense. It keeps sunlight and debris out, which is essential for preventing algae growth and ensuring an easier opening in the spring.
- Choose a Cover:
- Solid Covers: These block 100% of sunlight and debris. You’ll need a small pump to remove accumulated rainwater from the top.
- Mesh Safety Covers: These are stretched taut across the pool and anchored to the deck. They are the safest option, preventing accidental falls. Rain and snowmelt pass through, but leaves and debris stay out.
- Secure It Tightly: Ensure the cover is installed snugly according to its instructions. For standard solid covers, use water bags or blocks to hold it down. For safety covers, make sure all springs are properly tensioned. A tight fit prevents wind from getting underneath and keeps debris out.
8. Inspect Regularly
Don’t just cover your pool and forget about it until spring. A quick check every few weeks can prevent small issues from becoming big problems.
- Check the Cover: Make sure it remains securely in place.
- Remove Water/Debris: Pump any accumulated water off of a solid cover. Use a leaf blower or soft broom to remove excess leaves or snow. Too much weight can strain or damage the cover.
- Check Water Level: Ensure heavy rain hasn’t caused the pool’s water level to rise back up to the skimmer. If it has, pump some water out.
