Lowe's Home Improvement

Close Your Pool for Winter

After a season of swimming fun, closing your pool properly will make opening it much easier next season. Warm climate or cold, here are simple instructions for protecting your swimming pool during the off-season.

Tools and Materials Needed for Opening Your Pool

Pool skimmer and brush to clean the water surface and pool sides.

Balancers prevent corrosion and scaling, and ensure bather comfort. These products include pH increasers, pH decreasers, alkalinity increasers, calcium hardness increasers and chlorine stabilizers.

Sanitizers and shocks kill bacteria and help keep your water clear.

Algaecides prevent and kill algae.

Shop for Pools and Pool Accessories

Preparing to Close the Pool for the Season

Test Your Pool Chemical Levels

Having the proper chemical balance is important to prevent the water becoming too corrosive or producing heavy calcium deposits, especially during the off-season. Start the pool closing process by doing the following water balance tests:

Use a pool test kit to and this chart to measure water chemical levels following the manufacturer’s instructions.

Water Chemistry Test

Concentration Level




7.2 - 7.6



Total Alkalinity

80-125 ppm* for plaster/gunite pools

80-125 ppm* for plaster/gunite pools



Water Hardness(Calcium)

175-225 ppm


Chlorine Stabilizer

at least 30 ppm


Free Chlorine

1.0-4.0 ppm


*parts-per-million (ppm)


Before you begin closing your pool for the off-season, refer to pool equipment instructions. Also, make sure that you have adequate chemicals and tools for the job. If you have any questions about closing your pool, discuss the task with a Lowe's associate or call a professional for help.

Step 1

Check and adjust pH, the level of acidic and alkaline qualities in liquids.

  • Pool pH should be between 7.2 and 7.6.
  • If lower, add pH increaser.
  • If higher, add pH decreaser.
  • After adjusting, wait one hour before continuing tests.

Step 2

Check and adjust water hardness to the proper level of calcium in the water.

  • Calcium levels should be between 175 and 225 parts-per-million (ppm) for all pool types.
  • To increase the level, add calcium hardness increaser.
  • To decrease, drain some of the water and refill with source water that has a lower calcium level.

Step 3

Check and adjust alkalinity (how well the water resists a change in pH levels) as needed.

  • Alkalinity should be 80-125 ppm for plaster/gunite pools, and 125-150 ppm for other pool types.
  • If lower, add total alkalinity increaser.
  • If higher, add pH decreaser.
  • After adjusting, wait two hours before continuing tests.

Step 4

Check and adjust chlorine level in the pool water. Chlorine is what kills all the bacteria, viruses and germs in the water. However, the sun’s UV rays can diminish its effectiveness, so pool water also needs a chlorine stabilizer.

  • Check the stabilizer level and adjust to 30 ppm.
  • Check the chlorine level and adjust to 1 to 4 ppm.
Always wear safety goggles and rubber gloves when working with the chemicals. Also make sure you read and follow each product’s directions including how to use and how to store the chemicals.

Cleaning and Storing Pool Equipment

Brush Pool Walls

Cleaning involves more than just scrubbing the pool walls. The addition of certain chemicals will help keep your water stable, so it doesn’t damage your pool equipment.

Step 1

Remove, clean and store pool ladders, diving board and other pool accessories.

Step 2

Clean pool walls and floor with a pool brush.

  • Use a pool skimmer to remove debris from the water.
  • Also clean the skimmer baskets.

Step 3

As needed, add scale, stain and metal control chemicals. Scales are heavy deposits of calcium that can damage your filter system, so preventive action is best. Refer to product instructions for specifics.

Step 4

Add granular chorine and let it circulate for six hours.

Step 5

Add algaecide as recommended to prevent the growth of algae on the walls and floor of the pool.

Step 6

Clean the pool filtration system:

Cartridge filters: Replace the filter as indicated by the filter pressure dial or the filter manufacturer. Some cartridge pool filters can be manually cleaned a few times before replacement.

1. Remove the filter and spray with water
2. Soak the filter in a filter cleaner.

Sand filters: Backwash the filter following the manufacturer’s directions. Need for backwashing is indicated by the filter pressure dial. Replace the sand bed as recommended. The following are typical steps for cleaning the sand:

1. Close the valves into and out of the filter.
2. Add filter cleaner at full strength to the filter top through the inspection port, anode port, sand fill or pressure gauge hole, whichever is applicable.
3. After one hour, open the valves and backwash the filter thoroughly.
4. Remove the drain plug.
5. Drain the filter and turn the multi-port valve to the closed position.

D.E. (diatomaceous earth) filters: Backwash the filter following the manufacturer’s directions. Need for backwashing is indicated by the filter pressure dial. Add additives or replace the D.E. as recommended by the filter manufacturer. Typical cleaning steps are as follows:

1. Remove the filter and clean with a filter cleaner to eliminate buildup of grease, oil and scale.
2. Inspect the septa for tears or stretching, and repair or replace as needed.
3. Clean the inside of the filter tank.
4. Reinstall the filter.
5. Make sure the drain plug is closed.

Final Pool Closing Steps

Step 1

Drain the pool’s water level to appropriate level below the skimmer opening.

  • For painted or natural finish pools with solid covers: 6" below the skimmer opening.
  • For plaster pools with solid covers: 1-6" below the skimmer opening.
  • For vinyl-lined pools: 1" below the skimmer opening.
  • For pools with mesh covers or no covers: 18-24" below the skimmer opening.

Step 2

Remove the directional fittings and install the freeze plugs.

Step 3

Shut off the filter pump, drain all equipment and store as recommended by the pool manufacturer.

Step 4

In extreme cold climates, add swimming pool anti-freeze. CAUTION: Do not use automotive anti-freeze.

Step 5

Install the cover over the pool and secure. You may need some help with this step.

Do not walk on the cover, and do not allow children and pets to play near the pool unsupervised.

Warm Climate Pool Maintenance

In warmer climates, you may not need to close the pool. Following are a few maintenance steps for periods when your pool is inactive.

Step 1

Test and adjust water conditions as described above.

Step 2

Establish a pool maintenance schedule based on pool temperature. If typical pool temperature is 55-70°F, check and adjust water conditions once per week. If typical pool temperature is 40-55°F, check and adjust water conditions once per month.

  • Maintain the chlorine level to 1-4 ppm. It may help to do a midwinter shock treatment • to keep your pool sanitized.
  • Maintain the normal pH of 7.2-7.6.
  • Maintain alkalinity levels to 80-125 ppm for plaster or gunite pools, and 125-150 ppm for all other pool types.
  • Maintain calcium hardness levels at 200-275 ppm for plaster or gunite pools and 175-225 ppm for other pool types.
  • Brush and vacuum the debris from the water as needed.

 Run the filter for at least 2 hours per day or as recommended by the filter manufacturer.

If freezing temperatures are forecast, make sure that all mechanical equipment is working properly. As needed, run the pool heater several hours a day to keep water from freezing in the lines. If not equipped with a heater, run the filter system to circulate water, which may help prevent freezing.