As colder months loom, pool owners face the task of preparing their pools for winter. The process, often known as winterizing, is not just about covering your pool and hoping for the best. Proper winterization safeguards the pool from potential damage, ensures its longevity, and sets the stage for a smoother reopening come spring. But what steps should you take, and why are they crucial? This guide will shed light on those very questions.
Preparing for the Pool Closure
Checking the forecast: Best time to start the closing process
Before diving into the task of winterizing your pool, a glance at the local weather forecast is essential. Why? Timing plays a crucial role. Closing your pool while it’s still too warm can lead to algae growth, complicating your efforts.
Conversely, waiting too long and letting freezing temperatures creep in might cause structural damage to your pool and its components. Always look for a stretch of days when the temperatures are consistently below 65°F but not freezing. This window is ideal for pool closure.
Assembling necessary supplies and tools
Winterizing a pool isn’t a task you just walk into. Preparation is the key. Compile a list of essentials beforehand. This might include water testing kits, chemicals, a pool cover, water bags or weights, plugs for your skimmer and return jets, and antifreeze (for pools in extremely cold regions).
Having everything at hand ensures a seamless process and reduces the chances of interruptions. Additionally, having a checklist will ensure that nothing is overlooked.
Importance of a clean pool before closure
You might wonder: “Why clean the pool if I’m just going to cover it up?” The answer is simple. Leaving debris, leaves, or algae in the pool over the winter can stain your liner or pool surface. This makes reopening in the spring a far more challenging task. Furthermore, organic material left in the pool can disrupt the chemical balance, potentially damaging your pool and making it a breeding ground for bacteria.
Adjusting the Pool Chemistry

Testing the water balance
Balanced water isn’t just for swimming. It’s pivotal for the pool’s off-season health. Before adding any winterizing chemicals, ensure that your water is properly balanced. Using a reliable water testing kit:
Importance of balanced pH: Maintaining a pH level between 7.2 and 7.6 is vital. A balanced pH ensures that other chemicals, like chlorine, work effectively. Plus, it protects your pool from potential corrosion or scale build-up.
Alkalinity and calcium hardness considerations: Alkalinity should range between 80-120 ppm, acting as a pH buffer. Calcium hardness, on the other hand, should be maintained between 180-220 ppm for vinyl-lined pools and 200-250 ppm for plastered pools. This prevents possible damage from water being too soft or too hard.
Shocking the pool
Now, “shocking” might sound intense, but it’s a pivotal step in the winterization process.
What is pool shocking? At its core, pool shocking is the act of drastically raising the chlorine levels for a short period. This eliminates bacteria and contaminants, providing a clean slate for the winter months.
Choosing the right type of shock: While there are multiple types of pool shocks available, calcium hypochlorite is often recommended for winterizing. It’s durable, has a long shelf life, and combats algae effectively. Remember, after shocking the pool, give it ample time (usually 24-48 hours) for the chlorine levels to return to normal before adding any winterizing chemicals.
Adding winterizing chemicals
Finalizing the chemical balance is a combination of art and science. It ensures the longevity of your pool and reduces the workload when spring rolls around.
Algaecides for winter: Algae can be a silent menace during colder months. A quality winter algaecide will prevent its growth, ensuring a clearer pool when it’s time to reopen.
Anti-freeze agents (for areas with deep freezes): Just as you’d protect the pipes in your home from freezing, pools in very cold regions benefit from pool antifreeze. Add these to the pool’s plumbing to prevent ice damage. Note: Pool antifreeze is different from vehicle antifreeze, so always ensure you’re using the proper type.
Physical Pool Preparation
Cleaning the pool
Dirt and debris can be more than just eyesores. Left unchecked, they can cause significant issues over the winter months.
Skimming and vacuuming debris: Consider this a final, thorough sweep. Skimming the surface removes floating debris, while vacuuming addresses the sediment and dirt that have settled at the bottom. The cleaner the pool, the fewer problems you’ll encounter when it’s time to reopen.
Brushing the pool walls: Algae and calcium deposits often cling to the sides and bottom. A stiff pool brush makes quick work of these stubborn spots, ensuring they don’t fester under the winter cover.
Lowering the water level
The water level in a pool during winter is not a mere arbitrary detail.
Proper level based on pool type (above-ground vs. in-ground): Above-ground pools need water to be lowered about 4-6 inches below the skimmer, while in-ground pools should be lowered 4-6 inches below the tile line. This precaution reduces the risk of freezing damage.
Draining considerations and precautions: Draining too much can cause structural issues, like a vinyl liner shrinking or, in some soils, an in-ground pool lifting out of the ground. Draining just the right amount ensures the pool’s structure remains intact while minimizing freezing risks.
Addressing pool equipment
Your pool’s machinery and accessories need attention too.
Cleaning and storing pool accessories (ladders, toys, etc.): Remove all removable accessories from the pool. Clean them with a mild detergent, allow them to air dry, then store them in a cool, dry place.
Winterizing the filter and pump: For most filters, backwashing will suffice. However, every part of your filtration system should be drained of water. If you have a heater, ensure it’s free of water too. Any water left inside can freeze, causing the equipment to crack.
Blowing out lines to prevent freezing damage: Any water left in your pool’s plumbing system can freeze, expand, and crack the pipes. Using a blower or a shop vac, blow water out of the system. Once done, plug the return jets to ensure water doesn’t seep back in.
Covering the Pool

Choosing the right winter pool cover
The right cover can make a world of difference in ensuring a smoother reopening come springtime.
Mesh vs. solid covers: Pros and Cons: Mesh covers allow water (like rainfall) to seep through but block larger debris. They’re lighter and often easier to handle, but they can let finer contaminants into the pool. Solid covers block everything, ensuring cleaner water, but they require a pump or method to remove accumulated water.
Cover security: Water bags, weights, and clips: Security is paramount. Floating covers can be weighed down using water bags, while anchored covers might use weights or clips. The goal is to ensure the cover stays put, guarding against debris and unexpected pool access.
Properly securing the cover
A cover that’s haphazardly thrown on will serve little purpose.
Ensuring a snug fit: Ensure the cover fits well around the pool’s perimeter. If it’s too loose, it may flap in the wind, allowing debris in. If it’s too tight, it might get strained and tear.
Checking for potential wear and tear: Even the best covers wear out over time. Before securing it, inspect your cover for any signs of damage, holes, or weak spots. Addressing these now can save a lot of headaches later.
Additional Winterizing Tips
Monitoring the pool even in winter
While your pool may be out of sight, it shouldn’t be entirely out of mind.
Regular checks: Every few weeks, it’s wise to inspect your pool cover for damage, water accumulation, or unwanted debris. Addressing these issues promptly ensures the cover’s efficacy and reduces the chances of unforeseen springtime complications.
Keep the area around the pool clean: Fallen leaves, snow piles, or other debris near the pool area can end up in the pool, especially if there’s a strong gust of wind. A cleaner surrounding area often translates to a cleaner pool underneath that winter cover.
Investing in a pool pillow
Though it sounds like a luxury item, a pool pillow can be quite practical.
Positioned in the center of the pool underneath the cover, this inflatable cushion absorbs the pressure from ice expansion. This reduces the risk of walls getting pushed outwards in above-ground pools, particularly when water begins to freeze.
Inflate the pool pillow to about 60% capacity, tether it to ensure it stays central, and then cover your pool. It acts as a buffer, taking on the brunt of the ice’s expansive forces.
Being cautious with chemicals
Winterizing your pool doesn’t mean dumping in chemicals and hoping they last until spring.
Never mix chemicals, especially chlorine and algaecide. When adding any chemicals, pour them in separately and give ample time between each addition. This ensures effective treatment without unwanted chemical reactions.
Winter can be long, and you might have some pool chemicals left over. Store them in a cool, dry, and well-ventilated place, away from direct sunlight. This preserves their potency and ensures they’re ready for use when needed.