When winterizing a pool, add the recommended amount of phosphate remover approximately one week before closing the pool and remove leaves and other debris from the water, skimmer and pump basket to prevent algae formation. Add a winterization chemical kit to prepare the pool for the winter, or balance the pH before shocking and chlorinating the pool. Allow chlorine tablets to fully dissolve before closing the pool.
When using a winterization chemical kit, dilute the chemicals in a bucket of water, pour the chemicals into the pool, and allow the filter to run until the chemicals are evenly distributed. When adding chemicals without a kit, allow the pump to run for one cycle after shocking the pool.
Next, clean the filter by backwashing it, or use a recommended filter cleaner. Avoid using acid to clean a diatomaceous earth filter before closing the pool. To prevent damage from freezing temperatures, disconnect and drain the pump and heater, and use a compressor to remove water left in the lines.
In regions with freezing temperatures, drain the pool so the water is 4 to 6 inches below the skimmer, and add antifreeze to the drain lines. In warmer climates, fill the pool to the top. Install the air pillow and pool cover immediately before closing the pool.