The first step in the closing your pool is to make sure your water chemistry is balanced. You should make sure that your pH, Hardness, and Total Alkalinity are all balanced to protect the surface of the pool from staining and etching.
Run Filter for 24 hours
Run filter for 24 hours to remove all debris present in the water.
Remove all debris from the pool. If necessary, vacuum the floor, and use a skimmer or leaf net to remove floating items. Clean the surface of the walls and floor with a stiff-bristle brush to ensure that no residue or dirt is present.
Remove all of the pool’s fittings, such as wall fittings, solar blankets, skimmer baskets, cleaners and lights. Pool accessories should be removed as well, including the ladder and diving board. Store all of these items inside for the winter to protect them from the elements.
Lower Water Level
Using the filter pump and setting the inlet to pull from the main drain, lower the pool’s water level to approximately 2 inches below the lowest return line. If your pool is lined with tile along the edge, make sure the water line falls below the bottom of the tile. In a vinyl-lined pool, it is not necessary to lower the water.
Drain Pump and Filter
Drain all pumping, filtering, heating, and sanitizing equipment to prevent any damage from freezing. If any water is left inside these items, they may freeze and crack when the temperature drops. A small pump and filter may be stored indoors for the winter. Otherwise, use a compressor or shop vacuum to make sure that all the water is blown out of the equipment.
Blow out lines (Inground Pools)
In an in-ground pool, the plumbing lines must also be blown out for the winter. Use a vacuum blower for the job, and finish by placing expansion plugs on the lines. If you do not want to blow out the plumbing, add an antifreeze product to the line. With an above-ground pool, simply detach the hoses that connect to the filter and pump, and add plugs to the outlets.
Lubricate O-rings, plugs, and valves; this will make it easier to open the pool in the spring.
Add a preventative algicide (12 oz. of No Mor Problems® per 20,000 gallons) to prevent algae blooms and bacteria, and add a stain inhibitor/chelator (2 pounds of Pool Stain Treat® per 20,000 gallons) to prevent staining during winter. Make sure to perform one last shock treatment.
The final step in the winterizing process is to install your pool’s cover. Make sure it fits correctly and inspect it for holes or damage in the surface material where debris may enter. For an in-ground cover, use some type of water bags to secure the cover in place. An above-ground pool cover is usually secured with cables.