How to Winterize Your Inground Pool

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If you have an inground swimming pool, it’s time to winterize your pool. Proper winterization is the key to protecting your pool through the winter. If you’re a DIY-er, follow the steps below to properly winterize your pool. Not into doing it yourself? Your local pool service company should be able to help you! If you need a local pool professional to help you, visit our dealer locator to find a professional near you today.

Winterize your inground pool in 7 easy steps:

modern house in the middle of nowhere outside on deck or patio in winter with firewood and table and chairs

1. Test and balance the water

Start by brushing the walls, emptying skimmer baskets and vacuuming, right down to the pool floor. Cleaning your pool before you close it for winter will mean less cleaning in the spring!

Balancing the water chemistry helps to protect against scaling and corrosion over the winter. Using a water test kit, adjust the water to the recommended levels of pH, total alkalinity, calcium (hardness) and chlorination.  This is a good time to add a winterization chemical kit. These kits put high levels of chlorine and algaecide in the water to prepare it for the long winter months ahead. You should consult with a pool professional to identify the right kit for your pool. 

2. Clean the pool

You need to clean your pool before adding winterizing chemicals. Brush and vacuum the sides and the floor. You’ll also want to scrub the pool up to the tile line.

3. Add winterizing chemicals

If you want to add a winterization chemical kit, do it now. These kits put high levels of chlorine and algaecide in the water to prepare it for the winter months ahead. Your pool retailer offers ready-made kits for this purpose; use according to the maker's directions. In the case of larger pools, you may be directed to supplement the kit with additional quantities of some chemicals, too.

Add winterizing chemicals by pouring them into a bucket and then into the pool. Some of these chemicals instruct you to turn on the pool filter while you add the chemicals. Make sure you do, especially if you have a vinyl liner pool—you don't want stains on your liner from un-dissolved granules or damage to your equipment from concentrations of chemicals in the water.

4. Lower the water level

You should never completely drain an inground pool when winterizing. Drain the water to below the skimmer mouth, but DO NOT EMPTY THE POOL! The expansion of the soil under the pool as the water in the soil freezes can cause your pool to lift right out of the ground; it needs the weight of some water to keep it firmly in place.

5. Winterize the pump, heater and filter

Disconnect your pump and filter. Make sure all water is completely drained from the pump. Remove the drain plugs from it, note, there may be one or two, which will trap water inside. Once you've drained the pump, turn it on for just a second or two (no more—the seal is vulnerable to damage) to expel any remaining water from the impeller.

If you have a heater, remove any drain plugs and drain it. To make sure there is no standing water inside, blow it out with a compressor or shop vac.

Remove all return jet fittings, yes, the entire fitting. If one cracks while removing it, don't panic! You can get a replacement come spring.  Remove all skimmer baskets.

Remove the filter hoses. Spray the cartridge filter elements and D.E. (diatomaceous earth) grids with Filter Cleaner, then rinse them clean with a garden hose. If you have a sand filter, clean it by backwashing. For D.E. filters, drain the filter tanks and leave the backwash valve open. DO NOT acid wash a D.E. filter at pool closing time; wait until spring.

Open the drain at the bottom of the filter to let out any water in the filter outlet; be sure to open the air relief valve on top if you have one. Put the multiport valve in the closed or "winter" position—blow the water out of it if necessary—and remove the pressure gauge.

Store any small plugs or parts you have removed from the pump, heater and filter in the pump basket, so they're easy to find next year. Put jet fittings and any other items that you remove in one of the skimmer baskets or with the other parts the pump basket to avoid loss.

6. Add the air pillow

Before you put on the cover, you'll want to install a flotation device in the center of the pool. This device needn't be anything fancy—it can be a "pillow" sold at your local pool retailer or a truck innertube. The float balances the rainwater and ice sure to form on your pool's cover over the winter. Even more important, it eases pressure on the pool walls by allowing winter's ice to push in on the flotation device, not outward on the walls. If you have a large pool, you may need two or more air pillows to prevent ice from damaging the structure of the pool.

7. Put the cover on

Finally, put the cover on the pool to protect it from polluting elements and prevent debris from getting into the pool. The winter cover is important for both the pool and the people around it. It's stronger than a summer cover, both to withstand the weight of snow and ice, and to protect people or pets from accidentally falling through the cover into the water.

The cover should be taut enough to prevent too much water and debris from accumulating and potentially damaging it. If you live in a windy area, use a winter cover seal to keep the wind from getting underneath the cover. If your pool is surrounded by a lot of trees, consider adding a leaf catcher, which can save you hours in dredging fallen leaves.

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