How to Winterize Above-Ground and In-Ground Pools

While winterizing a pool may not be necessary in all parts of the country, if you live in an area where winter temperatures drop to freezing or below, winterizing your pool properly is a key part of pool maintenance. Winterizing provides these benefits:

• Prevents debris from accumulating in the pool during winter
• Protects water lines, equipment and pool walls from damage caused by freezing water
• Helps prevent algae growth
• Helps keep your water balanced properly for next year
• Makes opening your pool easier

The steps below show you how to winterize an above-ground pool and an in-ground pool. Most of the steps are the same, but winterizing an in-ground pool requires some procedures you may not need for an above-ground pool, and you might need to handle other steps a bit differently. We’ll tell you the differences so you’ll know how to close a pool for winter — no matter which type of pool you have.

Closing a pool takes some effort, but it's a relatively straightforward DIY project if you're familiar with maintaining a pool. You'll be handling common pool-care tasks such as:

• Giving the pool and pool area one final cleaning
• Treating the pool water
• Taking care of the filtration system and water lines
• Covering the pool for the winter

Plan ahead and find a helper to make the work go more quickly. In most cases, if you've got your equipment, chemical kit and other materials together, you'll be able to finish in a few hours.

Learning how to winterize a pool begins with knowing the proper timing. Use the temperature as your guide. Plan on closing a pool for the winter once the temperature is regularly 65 degrees Fahrenheit or lower. You may not be using the pool at this point, but if you close it while temperatures are still warm, you risk allowing algae to grow in the closed pool, creating more work for yourself in the spring. Waiting for cooler temperatures will help prevent algae growth. Winterizing too early may also reduce the effectiveness of the chemicals between the time you close the pool and open it in the spring.

You can wait a bit beyond the 65-degree point, but to prevent damage to the pool or filter system, make sure you have the work done before the temperature drops to 32 degrees Fahrenheit. Continue to filter, test and balance the water until you close the pool, even if you’re not using it. This continued maintenance makes the winterizing job easier.

Give the pool a thorough cleaning before you close it. Balancing the water during winterization will be easier with the water and surfaces clean.

Having the water clear and properly balanced for the winter can lead to a smooth opening in the spring.

Backwashing cleans the filter element by reversing the water through the element directly to the waste line.

You can disassemble a cartridge filter system and store the filter element for winter. You don’t need to disassemble sand filters unless you’re changing the sand.

You can also clean and store a diatomaceous earth (DE) filter.

Clearing lines for an above-ground pool is often as simple as disconnecting them and letting the water drain out. Store the lines in a dry, warm location.

If you have an in-ground pool, clearing the lines is a process that’s best left to professionals, especially if you have an older system. The following general steps show you how some pros clear pool lines with an air compressor connected to the pool pump.

Make sure your filter system is winterized and ready for the off-season.

Inspect your pool cover before you start this step.

Here are some quick answers to some of the most common questions about winterizing or closing a pool.