How to Close Your Pool For the Winter


As cold weather approaches, it’s time to start thinking about winterizing your swimming pool. Winterizing – or shutting down your pool for the season – helps safeguard your pool from costly damage related to freezing water. It’s also a great way to keep your pool clean and ensure that it’s ready to go when the next swimming season rolls around.

Have questions about how to close a pool? New to the whole winterizing thing? Here are a few steps to follow that will make your pool as safe as possible for the winter.

What is Winterizing?

1. Balance Your Water

Before you shut down your pool for the season, you’ll want to make sure that your water is balanced. By ensuring that your pool water chemistry is where it needs to be, you can avoid labor-intensive maintenance headaches when it’s time to open your pool up again.

Know the Lingo: Parts Per Million

Parts per million – often abbreviated as PPM – is a unit of measurement that tells you how much of a particular substance – such as a chemical or mineral -- is present in water.

This is where a good test kit is essential. You’ll want to test your swimming pool water for the following:

  • pH. This is a measure of the acidity of your pool water. pH level can affect everything from algae growth and corrosion to comfort and cleanliness. It can also affect the effectiveness of the other chemicals in your swimming pool. An ideal pH is 7.2 and 7.8 parts per million (PPM). If your pool’s pH is too high or too low, you can use a chemical increaser or decreaser as needed.
  • Total alkalinity. Alkalinity directly affects your pool’s pH. For example, if your swimming pool’s total alkalinity is too high, your pH will also be too high. If your alkalinity is too low – you guessed it -- your pH will also be too low. You’ll want your pool’s alkalinity to be around 100 PPM.
  • Calcium hardness. Calcium is always present in swimming pool water. However, when calcium levels are too high or too low, you could be looking at a range of issues such as corrosion and scaling. Aim for a calcium content of 100-400 PPM. Use a hardness increaser to raise calcium levels, and use a sequestering agent to lower your calcium (both products are available in any pool supply or hardware store).

Pro tip:

Closing your pool for the season? Consider investing in winterizing chemicals to keep your pool water chemistry balanced and on track. You can visit a local pool professional retailer to learn more.

2. Add a Shock Treatment

One critical component of pool closing: chlorine level. Chlorine prevents algae, breaks down bacteria, and keeps your pool clean and fresh. Before you shut things down for the season, it’s a good idea to hit your pool with an extra-powerful punch of chlorine in the form of a shock treatment. Shocking your pool is easy: Use a shock treatment to bring your 10 to 12 PPM. Then, wait a day or two for the chlorine to come down to its normal level, about 1.5 to 3.5 PPM.

Pro tip:

For best results, shock your pool a few days before you plan to shut it down.

3. Remove and Clean Pool Equipment and Accessories

Remove all skimmer baskets, heaters, slide, wall fittings, vacuums, pool cleaners, ladders and handrails. Clean all items, allow them to dry thoroughly, and store them in a safe, dry place. Once the equipment is out of the way, remove all debris from the pool using a net, a soft broom, or even a leaf rake.

Winter is Coming. Call the Pros.

Each type of swimming pool has unique requirements for winterizing. An above ground pool might have slightly different winterizing needs than an inground pool. Each type of pool filter has a unique shutdown process. Check with your pool professional to learn how to properly winterize your pool, minimize damage, and ensure safety.

4. Lower the Water Level

You can either use your filter pump or a submersible pump to lower your pool water level. You'll need to lower the level about 4 to 6 inches below the lowest plumbing line, normally the water return line. Be sure the water level is at least below the skimmer. You can remove the above ground pool skimmer.

5. Drain Your Pool Pump, Filters, Heaters, and Chlorinating Equipment

Your pump, filter, heater, and chlorinator all have a drain plug. Either drain the water out of these or blow the lines out with a shop vac. From there, it's time to clean your pool filter: Sand filters and Diatomaceous Earth (DE) filters will need to be backwashed, then disconnected and stored in a safe, dry place. Cartridge filters must be thoroughly cleaned and allowed to dry completely (this is also a good time to inspect your cartridge filter for any damage).

If the filter is small enough, you might be able to take it apart and store it for the winter. Keep the plugs out of these units. If you plug them back up and water happens to get into them, they might freeze over and crack your equipment.

Pro tip:

Place all the plugs in the skimmer basket during your pool winterization maintenance. That way, you'll know where they are when you need them next spring.

6. Empty Your Chemical Feeder

If you have a chemical feeder, drain and empty it. Leaving chemicals in your chemical feeder during swimming pool winterization can damage your equipment. Remember to put the top back on the chemical feeder and be sure to wear safety goggles and gloves.

7. Add a Winter Cover

Use a solid swimming pool cover that keeps out all debris, block the sun, and inhibit algae growth. And don’t forget the air pillow! Air pillows to fit under your winter pool cover, and they help relieve pressure -- and protect your pool’s walls -- as your pool water freezes. Air pillows can also keep leaves, debris, and water from collecting in the center of your pool cover.

Pro tip:

Don’t let your winter cover bow to pressure. Consider a pool cover pump to remove water and melted snow before they cause damage.

Have pets? Have kids? Safety first!

Safety covers are purpose-built to be stronger than standard winter swimming pool covers. Safety covers are a bit pricier, but many swimming pool owners find that the extra cost is worth it: Safety covers last longer (if they’re properly maintained and stored, of course), and they’re strong enough to keep unattended children and small animals from falling in the water.