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How to Winterize an Inground Swimming Pool

Make sure you have all of the tools and supplies you will need: basic hand tools, an air compressor or shop vac, winterizing plugs and gizmos, winterizing chemicals, pool cover and water tubes.

Pool should be vacuumed and the water should have all chemicals balanced PRIOR to closing. Pay particular attention to your pH, Alkalinity, Calcium and Chlorine levels prior to closing. Ranges: Alkalinity 120-140, Calcium 200-400, pH (7.2-7.8), Chlorine (3 to 4ppm)

Add your winter chemicals to the water. Follow the instructions on the containers. It usually is a good idea to thoroughly brush the walls and floor of the pool after the chemicals have been added. Let your pool circulate for one hour.

Lower the water level in the pool to just below the skimmers. This is a good time to give your filter a very thorough backwashing.
Prepare to blow out the underground plumbing lines by first draining the filter tank (put the drain plug back in after it is drained, while you are blowing out the lines). Connect your compressor or shop vac to a convenient point in the system (usually on the pump) and proceed to blow out all of the underground lines. Typically you would close the skimmer and main drain valves and blow out the return lines first. Returns can be blown out and plugged while still underwater just make sure to get the plugs in tight while the air pressure is still blowing out. Antifreeze can be added for the return lines through the pump strainer pot.
Next open the Main drain valve and blow out until air bubbles up and then close the valve to air lock the line for the winter. Finish by opening the skimmer valve and blowing them out. Skimmers lines can have non toxic antifreeze poured into the lines for extra caution before gizmos are used to plug the lines from the inside of the skimmer.

Disconnect your pump and remove all drain plugs, gauges and sight glasses. Detach motor from pump housing. Store in dry location. Put all small parts inside the pump strainer basket so they are not lost over the winter. O-rings should be lubricated with silicone lubricant. Usually pumps/motors should be stored out of the elements for the winter. Turn off circuit breaker.

DE filters should be opened and the elements cleaned off and inspected. If you leave your DE filter outside for the winter, make sure it is drained, but put the drain cap back on loosely. Many DE filters have very large drains holes and if left open are a very inviting entrance and winter home for small critters.

Sand filters should be backwashed and left with the drain caps removed.

Cartridge filters: Remove cartridge, clean and store in dry place. Drain filter tank, suck out water with wet vac, add 8 oz antifreeze and leave filter cap loosely attached.

Heaters need to be drained and blown out and chamber filled with antifreeze. Pressure switches will need to be drained. Trays can be removed from gas heaters but a trained pool professional should do this work. Turn off valve for gas supply. Keep in mind that repairs to a damaged heater can be very costly and could easily obscure any savings gained from doing it yourself.

Pools with Salt-Chlorine Generators. Winterize the Cell according to manufacturer instructions. The cell usually is cleaned with a 4:1 water to muriatic acid solution, and, typically, this also means disconnecting the power source and draining all water from the unit and wrapping it for storage. If the generator cell is to remain connected and is located below the pool water level it should be disconnected from its power source and protected with a non-toxic antifreeze.

Drain and clean your automatic chlorinator.

Now remove your ladders and diving boards for winter storage. Rinse and store in a dry place. Lubricate all bolts and store loose parts with your skimmer baskets and return fittings. Take off float lines, thermometers etc.

Pool Lights can be left in their niches. Turn off breaker for light or remove fuse.

Install your winter cover. If you are using a spring type safety cover, put all of the anchors in the up position first and connect one end before pulling the cover across the whole pool. Make sure to maintain the appropriate water level in the pool through out the winter with this type of cover. Most manufacturers recommend that the level be no more than 18” below the cover so there will be less stress on the cover when there is a heavy snow load on it. If you are using a solid cover with water tubes, spread the tubes around the perimeter of the pool and fill them approximately 80% with water. This allows for expansion when they freeze and keeps them from rolling. When putting the solid cover on the pool make sure that it is not put on tight. It needs to be put on so when rain accumulates on the cover it will not pull the sides in.

When done, inspect your work and make sure you have taken every precaution to minimize the potential for damage from freezing and other winter elements. Duct tape can be used to block open lines. Styrofoam can be used for additional protection from ice expansion.

Pools that have water falls, spas, solar heat and other water features will require special attention in winterizing and may best be handled by a pool service company. If you have any questions, be sure to contact your local pool professional.