How to close an above ground pool

In detail: balance the water (pH 7.4–7.6, alkalinity 80–120 ppm), shock it following your product's label, lower the water just below the skimmer, drain and store the pump and hoses, then cover the pool over an air pillow. Example: for a 5,000-gallon pool at pH 7.8 and alkalinity 70 ppm, balancing takes 1.4 lb of baking soda, then about 4.4 fl oz of 31.45% muriatic acid.

When to close (water temperature)

Close when the water has cooled for the season, not on the first cool weekend. A widely used rule of thumb is to wait until the water stays below about 65 °F: algae grows much more slowly in cold water, and whatever chlorine you leave behind lasts longer. It is a practice, not a standard, but the logic holds: a pool covered in warm September water often opens green in spring. The other deadline is frost: get the pump, hoses, and filter drained and indoors before nights drop below freezing.

If your water is already cool and nights are getting colder, now is the time to close. Closing takes 2–3 days from the first test to the cover.

Final water chemistry and doses

Do this 2–3 days before you put the cover on, so you have time to retest. The calculator at the top plans the closing steps for your gallons, with the shock step done by the directions on your product's label.

Closing targets for a vinyl-lined above-ground pool:

• pH: 7.4–7.6.
• Total alkalinity (TA): 80–120 ppm.
• Calcium hardness (CH): 150–250 ppm; don't add calcium just to close.
• Stabilizer (cyanuric acid, CYA): 30–50 ppm. It stays in the water over winter and protects the chlorine you add.
• Free chlorine (FC): shock on closing day, then let it drift down under the cover.

The closing shock. Use a product labeled for shocking pools, at the shock dose on its label. Labels give that dose for a set volume, such as per 10,000 gallons, so scale it to your pool: a 5,000-gallon pool takes half. Don't go above the label dose. Why shock at all? The pool will sit for months with no filtering or testing. A shock clears out what the filter missed before the cover goes on. Don't know your gallons? Check the Intex model list or the Bestway model list, or measure with the pool volume calculator. Always follow the product label.

Step by step

1. Clean the pool. Skim, brush the walls and floor, and vacuum. Leaves left in the pool use up chlorine and stain the liner over winter.
2. Clean the filter. Rinse the cartridge or backwash the sand filter so the filter works well in the last days of circulation.
3. Balance the water. Test, then adjust alkalinity first, then pH, with the pump running and 30 minutes between products.
4. Shock. Pour liquid chlorine in front of the return jet in the evening and run the pump overnight.
5. Check that it held. The next morning, FC should still be above your normal target, and combined chlorine (CC, total minus free chlorine) should be under 0.5 ppm. If FC dropped to your normal level or below, something is still using chlorine: brush, clean the filter, and shock again as the label allows, then wait another night.
6. Add algaecide, if you use one, once chlorine has come down to the level its label allows.
7. Lower the water level to just below the skimmer opening (or as your pool's manual says) so ice can't crack the skimmer. Don't drain a pool that is staying up: the water holds the liner in shape.
8. Drain and store the equipment. Disconnect the hoses, drain the pump and filter, and store them indoors. Plug the wall fittings with the plugs that came with the pool.
9. Remove the ladder and accessories, rinse them, and store them dry.
10. Float an air pillow in the center and put on the winter cover, tied down all around. The pillow takes the pressure of ice and snow off the walls.
11. Write down your final readings and the date. In spring they tell you what changed over winter.

Frame pools: take down or leave up?

Traditional steel-wall above-ground pools are built to stay up all year and are closed with water in them. Seasonal frame and inflatable pools (Intex Easy Set, Metal Frame, Prism Frame, Ultra XTR; Bestway Fast Set and Steel Pro MAX) are different:

• Intex's support guide says to take the filter pump and accessories indoors before temperatures drop below 32 °F (0 °C). If you leave the pool up, it asks for balanced water, an Intex cover, an inflated air bag in the water, and plugs in the wall fittings.
• Several pool guides say Intex manuals recommend draining and taking the pool down if temperatures in your area reach 41 °F (5 °C). We could not confirm this on an Intex page, so read the manual for your model.
• To store a frame pool, Intex's guide says to drain it (to a sewer rather than the lawn, because of the chemicals; check your local rules), dry every part completely, dust the liner with talc so it doesn't stick, and store it between about 34 °F and 104 °F (+1 to +40 °C).
• For Bestway, follow the manual for your model. We did not find Bestway winter instructions online that we could cite.

If you take the pool down, you don't need the closing chemistry above: drain, dry, and store the pool. Chemistry for the first fill next year is in the Intex start-up guide.

How to fold up an above-ground pool

This applies to seasonal frame and inflatable pools you take down for winter. Steel-wall pools stay up.

1. Drain the pool completely, to a sewer drain rather than the lawn if local rules allow.
2. Take off the pump, hoses, ladder, and frame parts, and keep the small parts in one labeled bag.
3. Dry every part completely, including the liner seams. A liner folded wet grows mildew.
4. Dust the liner with talc so it doesn't stick to itself, then fold it loosely, following your manual's folding steps.
5. Store everything indoors, between about 34 °F and 104 °F (+1 to +40 °C), away from sharp objects and rodents.

Opening next spring

Take the cover off when the weather warms, clean it before you store it, and top up the water. Then test before adding anything: chlorine will be low or gone, pH has usually drifted, and stabilizer should be close to where you left it. Compare with the readings you wrote down in the fall. The full sequence is in the pool opening checklist. Closing an inground pool instead? The steps differ (lines, blow-out, plugs): see how to close an inground pool.

Printable checklist

• ☐ Water has stayed cool (about 65 °F or below)
• ☐ Pool skimmed, brushed, and vacuumed
• ☐ Filter rinsed or backwashed
• ☐ TA 80–120 ppm, pH 7.4–7.6
• ☐ CYA tested: ______ ppm; shock dose from the label for ______ gal: ______
• ☐ Shocked, and chlorine held overnight
• ☐ Algaecide added per label (optional)
• ☐ Water lowered below skimmer, wall fittings plugged
• ☐ Pump, filter, and hoses drained and stored indoors
• ☐ Ladder and accessories out
• ☐ Air pillow in, cover on and tied down
• ☐ Final readings written down: FC ___ pH ___ TA ___ CYA ___ date ___

FAQ

Can I close my above ground pool without draining the water?

Yes, and for a permanent steel-wall pool you should: lower it only to just below the skimmer and leave the rest in, because the water holds the liner and walls in shape. Seasonal frame pools are different: many manufacturers expect them to be drained and stored in cold climates, so check your manual.

What chemicals are needed to close an above ground pool?

A test kit, a chlorine product labeled for shocking (liquid chlorine, for example), baking soda or acid to set alkalinity and pH, and optionally an algaecide. Stabilizer is only needed if CYA is below 30 ppm.

Do you put algaecide or shock first when closing a pool?

Shock first. Let chlorine come down to the level the algaecide label allows, usually a day or more later, then add the algaecide. The label tells you how high chlorine can be when you add it. Follow the label over any general advice.

Sources

• Intex Support, Getting the pool ready for winter: intexsupport.com
• CDC, Home pool and hot tub water treatment and testing: cdc.gov
• Targets and dose formulas: our methodology page