Water Chemistry

• The most important step to winterizing an inground pool is to make sure that the water left in the pool has the proper balance of chemicals. Otherwise, you may have to deal with corrosion or a build-up of hard water stains over the winter. The pH balance should be between 7.2 and 7.6, chlorine should be between 1 and 3 parts per million, calcium hardness should be between 175 and 250 parts per million and alkalinity should be between 80 and 120 parts per million. In addition, you should add winterizing chemicals to your pool water so that the quality of the water is maintained throughout the winter months.
  
  

Cleaning

• Before winterizing the pool, thoroughly scrub down the sides and bottom to remove any debris. Clean the filter and the pump basket, and take any excess chlorine out of the chlorinator. Take away any detachable items such as ladders or safety rails as well. A good cleaning will keep stains from developing over the winter and prevent you from having to deal with a mess come spring.
  
  

Water Levels

• Water level is very important when properly winterizing a pool. Frozen water expands, which can cause cracks and fissures in the cement lining of the pool. But neither should you drain the water out of the pool completely, because it leaves the pool more vulnerable to the elements. Instead, use a pump to drain the water below the returns, which are the jets that circulate water into the pool. Make sure the water level is below the skimmer as well.
  
  

Return Lines and Drain Plugs

• Remove any drain plugs from the filter tank and similar pieces of equipment before winter sets in. Store them out of the weather with the rest of your pool supplies (somewhere heated if possible). Prepare the return lines for winterization first by sealing them with threaded plugs and then slowly pouring antifreeze in through the filters. Use 1 gallon of antifreeze for every 10 feet of return line you wish to protect.
  
  

Pool Covers

• As a final step, place a pool cover over the top of an inground pool, sufficient to cover the entire surface of the pool. Secure it with weights to prevent it from becoming dislodged by the weather. Experts suggest using water-filled tubes as weights--available at most pool supply stores--rather than bricks or concrete blocks (which can damage the cover). You may also wish to use a cover pump--placed in the center of the cover--which will keep it clean of rain water or melted snow. If too much water builds up on the surface of the cover, it could tear or become dislodged.