How to Winterize a Saltwater Pool

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You need to know how to winterize a saltwater pool if you have cold winters with freezing temperatures. On the other hand, winterizing is more or less optional for homeowners who live in warmer climates, but it's still a good idea unless you enjoy taking dips or doing laps in cold weather. Actually, many people do, especially if there's a hot tub nearby to take away the chill, but that's something Northerners can only dream about because salt water can and does freeze.

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The process for winterizing a saltwater pool isn't much different from that for a standard swimming pool, and it's important to choose the right time to do it. The process can take up to a week, so plan ahead to give yourself time before the weather gets too cold.

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Why You Should Winterize Your Saltwater Pool

If you get freezing temperatures in the winter, the number-one reason for winterizing your saltwater pool is to prevent the water circulation lines from freezing and bursting during the winter months. There are a few other reasons as well. Winterizing prevents damage from ice to the vinyl pool liner of an above-ground pool. Moreover, if you don't winterize the pool and simply cover it, you'll have a nasty cleanup in the spring. Stains on pool surfaces caused by debris and minerals in the water can be difficult to remove.

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Will My Saltwater Pool Freeze?

Yes, a saltwater pool will freeze. The concentration of salt in seawater simply lowers the freezing point from 32 degrees Fahrenheit to about 28 degrees. The concentration of salt in a saltwater pool is about 10 times lower than in seawater, but the effect on the freezing point is about the same. A saltwater pool will also freeze at 28 degrees Fahrenheit.

When to Close a Saltwater Pool for the Winter

Most experts agree that you should close and winterize your saltwater pool when the water temperature stays consistently around 65 degrees Fahrenheit (18 degrees Celsius). Some recommend waiting until the temperature reaches 50 degrees Fahrenheit (10 degrees Celsius) because algae is less likely to grow in colder water. Winterizing and covering your pool when the water is warmer than 65 degrees Fahrenheit, on the other hand, is a bad idea because it promotes algae growth.

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Water cools faster in colder climates, obviously, so the best time to close your pool depends on where you live. The table below may help. If you aren't sure when to winterize, do what many pool owners do: Close the pool just after Labor Day and open it on Memorial Day.

Best Time to Close a Saltwater Pool

Region

When To Close Your Pool

Northern states, including Minnesota and Wisconsin as well as most of Canada

Mid-September to early October

Eastern seaboard states from Maine to Washington, D.C.

Mid-September to mid-October

Central states

Mid- October to late October

West coast

Late October to late November

Southern states from Arizona to Florida

Pools can stay open all year

Do You Need to Close a Saltwater Pool in a Warm Climate?

If you don't live in an area with freezing temperatures, winterizing your pool is optional, but there are good reasons to do it:

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  • Low temperatures decrease water conductivity, fooling the chlorine generator into recording a lower salt concentration than actually exists. This may prompt you to add more salt during the off season when it isn't needed, and because salt is corrosive, you may damage pool equipment and the pool liner.
  • You avoid spending money for pool maintenance and electricity for the pump when the air is too cold for swimming.
  • Winterizing and covering the pool protects the water from overacidification due to winter rain.

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Things You'll Need

How to Winterize a Saltwater Pool

1. Clean the Pool

Remove debris from the pool using a skimmer net and vacuum, and give the pool walls a good scrubbing with a pool brush or a scrub brush. Not only will this make the pool easier to open in the spring but it will also prevent contaminants from fouling the water. Disconnect and remove all metal parts, such as ladders and slides, and remove toys, lawn chairs, and the like from the pool deck.

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2. Balance the Pool Chemicals

Test the water chemistry — pH, total alkalinity (TA), and calcium hardness — about a week before the closing date. The pH level should be between 7.2 and 7.8, the TA between 80 and 120 ppm, and the calcium hardness between 200 and 400 ppm. Also check the free chlorine level, which should be between 1 ppm and 3 ppm; if it is low and you need to shock the pool to bring it up, now is the time to do it.

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3. Add Winterizing Chemicals

Purchase a winterizing kit. Pool closing kits are available specifically for saltwater pools, but a kit designed for chlorine pools will work, too. It contains an algaecide, a stain sequestrant, and other winterizing chemicals. High chlorine levels will break down the algaecide and promote algae growth, so double-check the chlorine and wait for the level to drop to a value between 1 to 3 ppm before you add the winterizing chemicals. Test the salt level with testing strips. The ideal level is 3,200 ppm, but it's fine to let it fall a little lower to help prevent stains, so don't add more salt.

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4. Lower the Water Level

Partially drain the pool by backwashing the filter using the drain plug or using a submersible pump. The water level should be just below the main skimmer and upper return jet for an above-ground pool and 6 inches below the skimmer for an in-ground pool. If you use a mesh cover on an in-ground pool, the water level should be 12 inches below the skimmer to allow for rain and snow melt. If you have a faceplate-style skimmer plug, you can install that on the skimmer in lieu of lowering the water level.

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Warning

Follow the manufacturer's recommendations for lowering the water level. Removing too much water can damage a pool.

5. Winterize the Pool Equipment

Unplug the saltwater generator and winterize it according to the manufacturer's instructions. You may be able to simply take it indoors, or you may be instructed to fill it with nontoxic antifreeze. Cut power to the pool pump and pool filter, disconnect the hoses, and remove the drain plugs. Blow water out of the hoses with a wet/dry vacuum. Use the vacuum or a compressor and air hose to blow water through the skimmer and return plugs to empty the pool lines of water. If you have a skimmer plate, install it now along with plugs for the return valves.

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6. Cover the Pool

Drop an air pillow or two in to support the pool cover and break up ice that forms. Then, install a winter cover according to the manufacturer's instructions. Weight the edges of the cover with water bags to keep them secure and prevent them from flapping in the wind.

When Can You Reopen a Saltwater Pool?

The best time to reopen a saltwater pool is when the temperature stays consistently above 70 degrees Fahrenheit. This minimizes algae buildup and makes the pool available for swimming earlier in the season. Waiting until the weather turns hotter can lead to increased algae growth, as the pool water gets hot while the circulation pump is off.

Signs You Didn’t Winterize Your Saltwater Pool Correctly

You might know the basics of how to winterize a saltwater pool, but if you don't do a good job, there will be consequences.

  • Pool lines with water in them could burst, and fixing the leaks could involve cutting through the pool deck.
  • Pool equipment, including the pump, filter, and saltwater chlorinator, could be damaged, and if you have a vinyl pool liner, it could be damaged by ice.
  • Finally, the pool walls and bottom will probably be stained, and you may have to drain the pool to clean them properly.

Is It Necessary to Drain a Saltwater Pool?

It is not necessary to completely drain a saltwater pool. However, you must prevent water from getting into the pool lines during winter. If you have a skimmer cover and plugs for the return lines, draining usually isn't necessary at all. If you don't have a skimmer cover, you have to drain enough water to bring the level far enough below the skimmer to ensure none can get in.

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