Before closing your pool, ensure it’s as clean as possible to prevent the growth of bacteria. Dirt and debris in the pool can lead to staining, clog the filtration system, and make the pool much harder to clean come springtime. Follow your typical process for cleaning the pool, taking extra care to remove dirt and grime.

If you own a robotic pool cleaner, run a complete cycle, from 1.5 to 4 hours, depending on the size of the pool, the type of robotic pool cleaner you own, and how much dirt has accumulated. If you’re cleaning the pool manually, vacuum and brush the pool thoroughly to remove dirt from the sides and bottom. Scrub the sides if mold or grime has built up. Remove debris with a handheld pool skimmer, and then clean out the skimmer basket.

NOTE: That vac is recommended & since the water level will need to be dropped for the winter, we can utilize this water to vac the pool. So vac to waste until the water level has dropped to near the bottom of the skimmer. Then remove the vac/hose & proceed to step 2.

If you live in a region with frigid temperatures that put your pool at risk of freezing, it’s important to lower the water level before closing your pool for the season. If you live in a climate where temperatures rarely dip below freezing, this step might not be necessary.

The target water level depends on your pool’s cover and surround.

• Mesh cover. If you have a mesh cover, lower the water to about 12 to 18 inches below the returns.
• Solid cover. If you have a solid cover, aim for a water level that’s 3 to 4 inches below the returns.
• Tile surround. If you have tile along the side of the pool, keep the water level between 1 and 6 inches below the tile to prevent damage to the tile.

For an in-ground pool, switch the filter to the “waste” setting and then turn it on, or use a siphon pump to bring the water level down.

For an above-ground pool, lowering water levels isn’t necessary. Simply remove the outlet hose from the skimmer basket.

You’ve done it regularly all season long, and now it’s time to test and balance the chemicals in your swimming pool once more to ensure that the water is properly balanced before you close your pool for the season.

Use a pool test kit to measure the water’s pH level, alkalinity, and calcium hardness. Next, add chemicals as necessary to get the pH between 7.2 and 7.6, the alkalinity between 80 and 120 parts per million (ppm), and the calcium hardness between 175 and 250 ppm.

About a week before you plan to stop using the pool, add phosphate remover (phosphates promote algae growth) and stain and scale preventer, following the manufacturer’s instructions. These chemicals help keep the water clean and free of mineral buildup all winter long.

Even if the water is clear, use pool shock before you close the pool for the winter. Pool shock is a powerful oxidizer that destroys organic matter and gives a boost to the free chlorine that keeps the water sanitized. Make sure the shock you buy contains at least 65 percent available chlorine, and always follow the directions on the packaging for correct use.

In general, a 1-pound bag is enough for 10,000 gallons of water. Mix the product with some pool water in a large bucket. Then, with the filter running, pour the mixture into the pool.

Wait until the total chlorine level returns to a range between 1 and 3 ppm. This will probably take a few days. Next, add algaecide to help keep those tiny green pool-tinters at bay through the cold months. Choose a product designed for pool closings. The amount to use varies by pool volume; follow the instructions provided by the algaecide manufacturer.

A pool closing kit includes all the chemicals you should need to stabilize the water chemistry of your pool. Buying the kit might cost less than buying everything separately. Shop around online or check prices at your local pool supply store.

Residual water can freeze inside your pool equipment and water lines and cause them to expand and crack. To avoid wintertime damage, these components must be as dry as possible before you close up the pool. It might be necessary to blow out the lines with an air compressor or a shop vac. If it is impossible (or deeply inconvenient) to do this, you can head off ice-related problems with a swimming pool antifreeze.

The draining process is easier for above-ground pools: Simply take off all the hoses and remove the plug from the bottom of the filter. It’s important that owners of above-ground pools bring the pump in for the winter: Some pumps are meant to be permanent fixtures outdoors, but pumps for above-ground pools are generally not meant to be out in tough temperatures.

After the lines have been blown out, use a skimmer plug (measure to make sure you buy the right size) or insert a pool gizmo into each skimmer housing to prevent ice from forming and damaging the skimmer. Also remove the “eyeball” fitting from the return line and plug the opening. Check your plug before closing off the line. Panteliodis reports that one of the most common mistakes he sees homeowners make is that they continue to use rubber plugs after dry rot has set in.

To prevent expanding ice from damaging the sides of the pool, owners of above-ground pools are advised to use a pool pillow like this one from Swimline beneath the cover. Placed in the center of the pool and tied to its sides, this air-filled ring helps minimize the effects of ice in the pool and helps distribute precipitation more evenly across the pool cover. If you do use a pool pillow, don’t overinflate it, and be aware that if it leaks, contracts, or even pops in the winter, you may not be able to inflate or patch it.

For inground pools, a pillow is recommended only if you live in an area with especially harsh winters.

To ensure that the pool cover fits correctly over the pool, remove accessories like ladders and diving boards. This is also the time to remove skimmer baskets and other wall fittings from the pool.

Before putting them away for the winter, clean all pool accessories thoroughly and leave them out to dry on a clean surface. Store ladders, diving boards, and other peripherals in a clean, dry place during the offseason.

A well-fitting winter pool cover like this one from Robelle is essential for keeping your pool clean and clear while it’s not in use. There are two types of winter covers typically found on the market: mesh and solid vinyl.

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• Mesh covers are more affordable and don’t require any maintenance over the winter, but they can allow debris to get into the pool water.
• While a solid cover should keep the pool water clear, it does require a pump to remove the rainwater and melted snow that collects on the cover.

“If safety is a primary concern,” says Williamson, which is usually the case for homeowners who have children, “there is no substitute for a safety cover.”

Even while the pool is covered, be sure to follow safety precautions such as locking the gates of pool fences to avoid having a small child or pet drown in water that has accumulated on top of the cover.

Even during the winter, it’s still important to adjust and monitor your pool’s chemical balance. Check the chemical composition monthly during the offseason and add chemicals as needed to maintain desirable levels.

Try to preserve a pH of around 7.4 to prevent corrosion and scale from building up. Ensure the water is chlorinated at a level of 2 to 4 ppm to kill bacteria. Aim for alkalinity in the standard 80 to 120 ppm range. Look for a minimum calcium hardness of 200 ppm to prevent pool surfaces from staining.