Pool Closing Checklist: Prepare Your Pool for Winter

You splashed your way through summer, but now it’s time to prep your pool for frigid temperatures. Use our pool closing checklist to learn how to close a pool for winter and keep it clean and damage-free, whether you have an above ground pool or an inground pool. When the heat returns, your pool will be ready and waiting for pool parties and nonstop fun all summer long. 

How to Close a Pool for Winter in 11 Steps 

It’s time to take the plunge! Follow the steps below to learn how to close a pool for winter.

1. Do a Deep Clean

Leaving algae, leaves, and other debris floating through the winter isn’t a good look when you open your pool come summer. And worse, not keeping up with pool cleaning can lead to staining and damaging algae buildup.

Include the following tasks in your winter pool cleaning checklist:

1. Pour in a scale and stain remover a night or two before you plan to cover your pool. 

2. Use a skimmer net to scoop out all the leaves and other dirty debris.

3. Gently scrub the base and sides of the pool with a pool brush.

4. Use a pool vacuum to pick up the hard-to-reach fragments on the pool floor.

Check the Water Chemistry

Buy a pool testing kit to confirm the pH and calcium levels of your pool and adjust accordingly. If your levels are too low, it can lead to liner damage. You’ll need to raise your pool pH levels before closing it for winter if this is the case.

Aim for the higher ends of the ranges so the winterizing pool chemicals last longer through the covered months:

• Alkalinity: 80–120 parts per million (ppm) 

• pH: 7.3–7.6

• Calcium hardness: 175–225 ppm 

2. Shock the Pool Water

Shocking your pool helps to kill off any bacteria and algae before closing it. Chlorine and non-chlorine shock solutions are available. While chlorine-based products are more effective at removing algae, don’t use them in above-ground pools. The harsh chemicals can corrode vinyl and plastic pool walls.

To shock the water, follow these steps:

1. Wear protective eyewear and chemical-resistant gloves.

2. Carefully read the manufacturers’ instructions, as the process can vary depending on the type of chemical.

3. Slowly add the shock to a 3/4-filled bucket of warm water. Stir carefully until it is completely dissolved. 

4. If you don’t need to add the shock to the water, add it directly to the pool.

5. Walk around the pool while pouring the shock for more even distribution. 

6. Ensure the pump and filter continue to run for around 12 hours after adding the shock to help circulate it around the pool.

7. If your pool is particularly dirty, you might have to repeat this process several times.

8. Aim for safe chlorine levels between one and three ppm.

3. Add Algaecide (Optional)

Scrubbing and shocking should help inhibit algal growth, but if you’re concerned, you can add an algaecide too.

Apply at least 24 hours after shocking (mixing chlorine and algaecide together at the same time renders both of them useless), and select a product that’s safe to use alongside your shock chemicals. Properly circulate the algal treatment by running the pump for another 24 hours.

Alternatively, lift the cover of your pool every few weeks during winter and if you see any signs of algae growth, add the algaecide then.

4. Backwash the Filter

Backwashing your filter will help prevent algae from growing inside of it during the winter months. Begin by switching off the pool heater and filter. Then look for a valve on your filter that's labeled "drain to waste" or "backwash" and give it a turn. If your filter isn't already connected to a waste receptacle, you'll need to attach a backwash hose and connect it to your own waste bin. 

After your hose connections are in place, turn the filter on and run it for three to five minutes, or until the water runs completely clear. Once the water consistently runs clear, switch the valve to the rinse setting, letting it run for another 30 seconds before turning it off. 

Note: Backwashing only applies to sand filters, so if you have a removable filter, you can skip this step.

5. Lower Water Levels

Don't empty your pool of water in the winter, as this can dry out and damage the liner. However, you usually have to drain it slightly using a pump or hand siphon (unless you live somewhere it doesn't freeze). This part of the process varies depending on whether you have an above ground pool or an inground pool.

Above Ground Pool

• If you use a plate to cover the skimmer, you won’t need to drain any water.

• If you don’t use a skimmer plate, drain the water to just below the skimmer line. 

• Don’t drain the water too much, as it can’t support the cover when it collects snow.

Inground Pool

• If you live where the water freezes, drain the water to just below the skimmer or tile line. 

• The final level depends on your pool cover—check the manufacturer's instructions.

• Typically, you can lower the water around 12 to 18 inches below the skimmer with a mesh cover and three to six inches below with a solid cover.

6. Clean and Store the Drain Pump, Filters, and Other Equipment

You want to make sure you don't leave any water in your pumps, heaters, or filters. If you do, the water is likely to freeze and thaw throughout the winter, which can damage your equipment and promote mold growth. 

• Cleaning a cartridge filter: If you have a cartridge filter, open the pressure release valve, loosen the top of the filter housing, then remove the cartridge. Rinse the cartridge with a hose, removing any debris, then let it dry completely before storing it for the season.

• Cleaning a diatomaceous earth (DE) filter: To store a DE filter, start by opening the pressure release valve, loosening the housing, and removing the filter grids. Then clean it by lightly spraying it with clean water, using a hose or spray bottle, taking care not to damage the grids. Let them completely dry before storing for winter. 

• Cleaning a sand filter: If you have a sand filter, you can skip this step since you already cleaned it through backwashing during step four.

Once you clean your filter, it's time to store it for winter. Remove all of the filter system's plugs, as well as the pressure gauge and sight glass. You can store these inside the pump using the strainer basket. If you have an inground system, you can then cover your entire filter system, including the pump, with a tarp, using a rope to secure it. Just make sure the tarp isn't too tight, allowing enough air to flow through to avoid damage. 

If you have an above-ground system, you can simply bring it inside of your house or garage, storing it in a clean, dry area. 

7. Blow Out Pool Lines

Clearing the lines in an above ground pool is relatively straightforward, as they’re easy to access. Call in the pros if you’re unsure about following the instructions for draining the lines in your inground pool.

1. Remove skimmer baskets.

2. Remove screw-like return fittings that are found around the pipes.

3. Make sure the water you're blowing out goes in the right direction by turning the valve to the filter or recirculating position.

4. Attach the air compressor (and adapter if you need it) to the pump’s drain plug and turn it on.

5. When you see water leaving the pool skimmer and jets, turn the compressor off.

6. Clean water out of the skimmer.  

7. Once the skimmer is dry, block off the hole in it with a rubber skimmer plug.

8. Turn on the compressor again and watch for air bubbles coming out of the return lines (usually after a couple of minutes) and then plug them off too.

9. To move air toward and out of the main drain, set the valve in front of your pump to the main drain setting. After around a minute of running the air compressor, you should see bubbles at the deep end of the pool. Switch off the compressor at this point.

10. Turn your pump valve back to the skimmer line setting so it’s ready for next season.

Once you complete these steps, remove all winterizing plugs from your skimmer and add antifreeze to them. A little less than one gallon per line should do the trick. If you perfectly blew out the lines then this step isn't necessary, but it can help prevent freezing damage in case there's still some water left in your lines. Plus, it won't hurt your system, so it's a good precautionary measure to take regardless. 

8. Pop in a Winterizing Pill

Want to go a step further with winter protection? You can add a winterizing pill. They’re not essential but are wallet-friendly and easy to apply. 

This pool maintenance product is actually a floating pill that slowly releases enzymes to help prevent scale, stain, and bacteria buildup. The pill comes in varying sizes, depending on how much water your pool holds. 

Always check individual manufacturer instructions, but the simple process for adding a winterizing pill is usually as follows:

1. Shake the pill in its packet before opening.

2. Locate and remove the piercing tool.

3. Use the tool to pierce the recessed section of the pill.

4. Pop the pill into your pool and leave it to do its work over the winter.

9. Add an Air Pillow for an Above Ground Pool

Use this for above ground pools that don’t have the insulating wall protection that inground pools do. An air pillow sits between the water and the cover, helping absorb the freezing and thawing pressure. 

Always check individual manufacturer instructions, but the steps for installing an air pillow are as follows:

1. Allow for compression of the air pillow and only inflate it to between 60% and 80%.

2. Attach a strong string to the grommets on the pillow ends.

3. Pop the pillow into the center of your pool.

4. Tie the string taut to the pool edge to prevent the pillow from moving around.

10. Cover Your Pool

Unlike deciding whether or not to cover your AC for the winter, a pool cover for the season isn't optional. Keep your pool free from leaf litter and other debris by securing a weather-resistant and well-fitting pool cover rather than a flapping makeshift tarp. 

Mesh and solid vinyl are the two main types of pool covers available. Mesh covers are economical and low-maintenance, but small pieces of debris can sometimes sneak through the cover and into the water.

Solid covers are pricier and a pump is often needed to keep rainwater and snowmelt off the top, but they are better at keeping the pool debris-free.

Even with a cover, keep kids and dogs away from the pool area. Water that pools on the cover surface presents a drowning risk.

11. Monitor on a Monthly Basis

If you want to ensure your pool remains bacteria-, stain-, and scale-free through the winter, buy some extra kits to do monthly checks on your pool’s chemical levels. As a reminder, you’re looking for alkalinity levels of 80 to 120 parts-per-million (ppm), pH levels of 7.3 to 7.6, and calcium hardness of 175 to 225 ppm.

Why Do You Need to Close Your Pool for Winter?

You’ve put away the pool rafts and picked up all the beach towels—isn’t that enough? Actually, a common pool care mistake is not properly closing your pool for winter. 

In fact, there are lots of benefits to winterizing your pool, including the following:

• It prevents cracking or other freeze-related pool repair costs.

• It can extend the pool’s lifespan. 

• Your pool filter won’t have to work as hard to remove downtime debris.

• It keeps the pool clean and algae-free come summer.

• It reduces maintenance and repair costs down the line.

When to Close Your Pool for Winter 

The right time to close your pool depends on your climate, as well as your personal preferences. But a good rule of thumb is to consider closing it once temperatures are consistently below 65 degrees Fahrenheit. If you try to close the pool when it's still fairly warm out, algae can grow inside the closed pool, creating a mess that's tough to clean up. 

However, make sure you don't wait until the temperatures are 32 degrees Fahrenheit or lower, as freezing temperatures can potentially damage your pool and its electrical systems. 

How Much Does It Cost to Close a Pool?  

The cost to close a pool usually ranges from $150 to $400, but most homeowners pay close to $250 on average. Factors impacting cost include your pool's size, systems, and accessories. You'll also need to pay labor costs if you hire a pro to close it for you. 

Tips for Closing a Pool and Winter Maintenance

There are a few helpful tips to keep yourself and your pool safe and healthy throughout the winter.  

• When working with chemicals, always use goggles, rubber gloves, and a dust mask to prevent irritation.

• Add chemicals directly to the pool water or into a bucket of water. Adding water after the chemicals increases the chance of inhaling fumes and dust.

• If you live in a snowy region or you experience lots of rain, make sure to remove snow buildup and pools of water from the cover throughout the season so it doesn't weigh it down and cause damage. 

• Keep an eye on your equipment. Even when your pool is closed and covered, pollen, dirt, and other debris can make their way inside. Do periodic checks and wipe down any areas where you notice dirt and debris building up. 

• Add more algaecide midway through winter to help ensure clean pool water come spring. 

• Store all pool accessories in a clean, dry area without a lot of sunlight. Prolonged sun exposure can cause damage and discoloration.

• Open your pool before it gets extremely hot. The longer your pool is closed, the easier it is for bacteria and other algae to grow, so rather than wait for summer, open your pool once temperatures are consistently hitting 65 degrees or so. 

DIY vs. Hiring a Pro

It just takes a bit of elbow grease to skim debris and scrub pool walls, but getting it wrong with chemical levels can lead to safety issues and damage. 

If you only want to associate your pool with relaxation or you’re nervous about adding the right amount of chemicals, call in a local pool closing professional. They’ll also run a trained eye over the walls, filters, and other equipment. The longer you leave a leaky pipe or faulty filter, the higher the cost of the pool repairs.

Pros typically charge $50 to $100 per hour to help winterize your pool. So expect to pay $150 to $300 for this pool maintenance cost. Doing it yourself may cost $50 to $150, depending on whether you bulk buy the chemical products.