1. Temperature & Debris

Most people close their pools when the kids go back to school or by the end of September. When temperatures stay below 65°F (18°C) during the daytime (off-season) and frost at night, it is time to close. NOTE: Closing too early will allow algae to grow and cause a troublesome opening in the Spring.

Why? Algae needs sunlight and heat to thrive. Cold temps help keep your water clear of infestation. As a bonus, leaving your pool open longer with cold weather allows the opportunity to clean, test, and balance your pool before closing.

For those in a treed area, closing might be earlier if the leaves are falling heavily and are polluting the pool. 

2. Chemicals

Test the water yourself with test strips or liquid. If there is a SERIOUS concern then take a water sample to your local pool store and have them test it for you.

 pH should between 7.2 and 7.6, and alkalinity between 100 ppm and 150 ppm. Calcium hardness range from 175 ppm to 225 ppm. Chlorine between 1 ppm and 3 ppm. If you use a different sanitizer, just make sure it’s at the proper level for whatever you’re using. Since you won’t be adjusting the water balance during the offseason, it’s better to be on the high side of these ranges when you close your pool because they’ll naturally decrease over time.

Increase alkalinity by increasing the base using sodium bicarbonate to your pool water. Reduce with muriatic acid. Adjust alkalinity before pH because it has an impact on pH readings. Ensure that pH targets are met. Raising or lowering the pH is using the same chemicals as adjusting the alkalinity. Raise the pH with soda and lower with acid.

Hard water (typically from well water) deposits calcium in your pool and plumbing, forming a build-up over time. Too-soft water can also corrode metal.

If your water’s too hard, add salt. Too soft, add calcium chloride.

When using calcium hypochlorite or tri-chlor pucks, use fast-acting pucks that dissolve within 24 hours. Alternatively, use up your supply of liquid chlorine (sodium hypochlorite) as to not have to store it over winter. Using triple the normal amount will have no negative effect.

Add C-Poolandspa or an algaecide to your pool just before closing it to keep algae from invading over the winter. 

Also add (optional) a clarifying enzyme treatment ( such as C-Spa Non-foaming Enzymes) to further reduce algae growth, liner stains, and contaminant build-up. Add a few capfuls to the water, where they work all winter to help you greet spring with a clear pool. If you’ve struggled with a green, murky pool at the opening in the past, or want to avoid one in the future, using C-Poolandspa and C-Spa can help immensely.


3. Cleaning

It is the final cleaning of the season, so make it thorough. Vacuum the entire pool, brush down the walls, and skim the surface. Keep the filter running to clarify the water. Brush out any algae from the vinyl seats, stairs, and walls. A little prep now will save you from some potentially nasty surprises when you open your pool next spring. A clean pool makes it easier to properly balance your water. It also ensures nothing is left behind to feed algae or mold that might develop over winter. I recommend a super dose of liquid chlorine. It will not evaporate fast in the cold weather.

4. Drain and Filters

Water trapped in your pool lines can damage the lines by ice expansion. Even if winters are mild in your area, draining or blowing the lines is essential. Simply drain the pool down to below the return jets, PLUG the jets.  Allow all the water to drain throughout the system and the filter and pump (assuming they are the lowest point). Open up all the valves to allow for drainage. Plug the skimmer. Open the drain valve on the filter. If it is an easy disconnect, remove the pump indoors. If not, ensure no water is trapped inside the pump.

5. Protect Skimmer

Remove the skimmer basket and store it somewhere safe and dry for the winter. Insert a skimmer plug after the pool has been drained to the desired level. 


6. Winterizing The Pump

The Pump:

Completely remove all drain plugs to drain and remove the pool pump if able. If not ensure there is no trapped water by opening the pump drains or by cracking open the pump mechanism from the motor itself.  Store all the drain plugs (including the ones from the filter) in the pump basket so that you keep them all together and you won’t have to go hunting for them in the spring. 

The Filter:

Sand: The first thing you should do when winterizing your sand filter system is to perform a backwash. After the water is running clear from the nozzle, turn off the power. After you backwash, move the valve to the “rinse” position and let it run for 30 seconds. After a backwash and rinse, place the valve to the “winterize” setting on the top mount valve. This will allow water to drain from the valve. Next, Completely drain all the water from the filter tank. Unscrew and remove the drain cap on the bottom of the filter barrel. Put the cap away in the pump baskets. You do not need to remove any sand from the filter. Your sand filter system‘s sand is good for about 4-5 years.

Sand: Set your multiport valve to “Winterize,” and remove the drain plug at the bottom to allow the filter to drain completely. If your multiport valve has a bleeder valve and a sight glass, remove those too, and store them in the pump basket for easy retrieval next season.

Bring your filter indoors for winter storage. If the weight of the sand makes this too difficult, you can leave it outside if you remove all the drain plugs. With the plugs removed, freezing water or condensation that builds up inside the filter tank won’t crack it.

Diatomaceous Earth (D.E.): Drain it, then rinse off the grids (or fingers) with a hose to remove excess D.E. Leave the valves open. Otherwise, similar to sand filters.

Cartridge Drain it, then rinse off the cartridge with a hose. Leave the valves open, and store the cartridge indoors for the winter. Have a backup cartridge.

Note: Move your hardware indoors or have a protective cover after you disconnect. It extends your gear’s useful life and protects it from cold weather damage.

SALTWATER: If your pool uses a saltwater system, switch the chlorine generator to the “winter” setting, if it has one. If it doesn’t, most chlorine generators have a removable electrolytic cell you can access by unscrewing the end caps. Remove the cell, or your entire salt system if you prefer, and store it inside for the winter.

Note: Take a few moments to clean the cell before storing it. It’ll prolong its life and help reduce the risk of hardware problems when it’s time to reopen your pool. Flip the circuit breaker and make sure power and gas to the heater are off. Then store any controllers, robotic cleaners, and other electronics indoors for the winter.


7. Accessories

Gather up your pool ladder, floaters, toys, and any other accessories you may have. Leaving them in the pool can damage the items or, even worse, your pool. They could puncture the lining or start to rust. Corroded metal can contaminate your water and cause serious hardware problems.

Gather up all your accessories, then give them a good cleaning and let them dry. Then store them in a clean, dry place, away from direct sunlight, until spring.


8. Lower Water

Drain water well below the skimmer and to at least one inch below the return jets port. Plug the port snugly by screwing in the correct cap on each exposed port. Do not allow any water back into the lines as it will freeze and crack the lines.

9. Air Pillow

In cold climates, placing an air pillow under the cover protects the walls of your pool from damage. It compensates for the pressure of the snow and ice on top of the cover. A few pillows are essential is you are using a POOL SAFETY COVER because it keeps the cover level and allows leaves and snow to blow off.

If you close and cover your pool, use it to keep water and debris off to the side of the pool for an easy spring clean-up.


10. Pool Cover

Place the pool cover over your pool—and the air pillow. Bricks, stones, or anything else may damage your liner if it were to fall into the pool. Keep the cover dry. Pool safety covers are recommended for families with children and pets because they will not sink, collapse, or rip in the event that someone accidentally walks on them or a pet runs over them.