How to Open an Above Ground Pool for the Season
Open an above-ground pool in this order: clear and remove the cover, reconnect the pump and filter, top up the water, run the pump, then test and dose. For a 5,000-gallon pool that opens at free chlorine 1 ppm, pH 7.8, and alkalinity 70 ppm, that means 19 fl oz of 10% liquid chlorine, 1.4 lb of baking soda, and then 4.4 fl oz of 31.45% muriatic acid.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
On this page (10 sections)
This guide is for pools that stayed up over winter: steel-wall pools and frame pools left standing. If you took a frame pool down and are setting it up again, the water is new, so follow new pool start-up after the setup steps in your manual. Not sure it is time to open yet? See when to open and close a pool.
What you need
- A submersible pump or a pool cover pump, and a soft broom.
- A garden hose, and the hoses, plugs, and clamps you stored in the fall.
- A clean or new filter cartridge, or a sand filter cleaner.
- A test kit that reads free chlorine (FC), pH, total alkalinity (TA), stabilizer (CYA), and calcium hardness.
- Liquid chlorine, baking soda, and acid (muriatic or dry). Buy stabilizer only if your test shows CYA is low.
- Your notes from closing day, if you wrote the readings down.
Remove the winter cover without dumping it in
- Pump the water off the cover with a submersible pump, as the opening guides from pool chemical makers advise. A cover full of rainwater and leaves is heavy, and pulling it while full tips everything into the pool.
- Sweep off leaves with a soft broom or a leaf net.
- Loosen the cable or ties all around, then slide the cover off one side, folding it as you go so the dirty top stays folded inward.
- Take out the air pillow and any ice equalizer.
- Clean the cover, let it dry completely, and store it folded off the ground, away from rodents.
Reconnect the pump, filter, and hoses
- Wall fittings. Take out the winter plugs from the skimmer and the return fitting. On Intex pools with plunger valves, open the valves once the hoses are on.
- Hoses and clamps. Check hoses for cracks and replace any that are stiff or split. Tighten every clamp by hand before you add water to the pump.
- Cartridge filters (Intex, Bestway, most frame pools). Start the season with a clean cartridge. Intex says to replace its cartridges every two weeks for best results, and Bestway's Flowclear manual suggests the same two-week replacement. A cartridge that stays brown after rinsing is worn out; replace it. Sizes and types: Intex cartridge types and Bestway Flowclear filters.
- Sand filters (most steel-wall pools). Put back the drain plug and the pressure gauge, set the valve to "Filter," and backwash after the first day if pressure is already high.
- Pump. Check the lid O-ring, fill the pump with water if your manual says to prime it, and never run it dry. Pump questions for Intex models: Intex pool pump guide.
Top up and start circulating
Add water to the normal level before you start the pump. On a pool with a thru-wall skimmer, that is midway up the skimmer faceplate; Intex frame pools have their own fill line in the manual. Start the pump and check every fitting for drips.
Look over the liner while the water rises: a damp spot under a wall, a wrinkle that grows, or a level that keeps dropping can mean a leak. Mark the water level with a piece of tape and check it the next day.
Then let the water mix before the full test. One pool chemical maker's opening guide says to circulate for 24 to 48 hours. If free chlorine is near zero, don't wait that long: add chlorine as soon as the pump runs, then do the full balance test the next day. Take the sample at elbow depth, away from the return jet, as Taylor Technologies advises.
First test and start-up doses
Enter your test results. The calculator lists the doses in the order to add them, with the pump running and 30 minutes between steps.
In the example, a 5,000-gallon above-ground pool opens with FC 1 ppm, pH 7.8, TA 70 ppm, CYA 40 ppm, and calcium 250 ppm. The plan has three steps:
- Chlorine: 19 fl oz of 10% liquid chlorine, FC 1 → 4 ppm. At CYA 40, the minimum is 3 ppm.
- Alkalinity: 1.4 lb of baking soda, TA 70 → 90 ppm.
- pH: 4.4 fl oz of 31.45% muriatic acid, pH 7.8 → 7.5. Retest pH before this step, since baking soda moves it a little.
Stabilizer usually survives the winter, but rain overflow and draining lower it. If your CYA reads below 30 ppm, use the pool stabilizer calculator. Don't know your gallons? The above-ground pool gallons chart lists common models, and the 5,000-gallon dose chart has every dose for that size in one place. Always follow the product label.
Opened green or cloudy?
Green water under the cover means chlorine ran out over the winter. Brush, run the filter 24 hours a day, and treat with a product labeled for shocking pools at the amount on its label; the full process is in how to clear a green pool. Cloudy but not green usually points to the filter first: see cloudy pool water. Don't balance pH precisely while chlorine is very high; clear the water first, then balance.
The first week
- Test FC and pH every day. A newly opened pool often uses chlorine fast while the filter catches up.
- Clean or rinse the cartridge every few days, or backwash a sand filter when pressure rises.
- Brush the walls and floor and vacuum.
- Retest CYA and calcium at the end of the week, after everything has dissolved.
The weekly routine for the rest of the season is on above-ground pool care.
Printable opening checklist
- ☐ Water pumped off the cover; leaves swept off
- ☐ Cover removed, cleaned, dried, and stored
- ☐ Air pillow out; winter plugs out
- ☐ Hoses, clamps, and pump lid O-ring checked
- ☐ Clean or new cartridge in, or sand filter set to Filter
- ☐ Water topped up to the normal level; no drips at fittings
- ☐ Pump running; chlorine added if FC was near zero
- ☐ Full test: FC ___ pH ___ TA ___ CYA ___ CH ___ date ___
- ☐ Doses added in order, 30 minutes apart
- ☐ Retested; FC at or below the label's swim limit before anyone swims
Safety
Never mix chlorine and acid, or two chlorine products, and never pour them into the same bucket. Add each product to the pool separately with the pump running, 30 minutes apart. Add chemicals to water, never water to chemicals. Wear gloves and eye protection. Unplug the pump before you work on it, and keep electrical cords away from the water. Leftover chemicals from last year may have lost strength or caked; check the labels and store them apart. Poison Control: 1-800-222-1222. Always follow the product label. It is a violation of federal law to use a pesticide product in a manner inconsistent with its labeling.
FAQ
Do you need to shock an above ground pool when opening it?
Only if the water is green or cloudy, or chlorine won't hold. Clear water with FC above the minimum for your CYA needs only normal doses. If you do shock, use the amount on the product's label.
Should you drain an above ground pool to open it?
No. The water holds the liner and walls in shape, and an empty above-ground pool can be damaged. Top it up instead. Replace part of the water only if a test shows a reason, such as very high stabilizer.
How long does it take to open an above ground pool?
The work takes a few hours. Plan on a few more days of running the filter, testing, and adjusting before the water is fully balanced.
When can you swim after opening an above ground pool?
When your test shows FC at or above the minimum for your CYA and at or below the swim limit on your chlorine label, pH in range, and at least 30 minutes have passed since the last chemical with the pump running.
Sources
- Intex, Type A filter cartridge (replace every two weeks): intexcorp.com
- Bestway, Flowclear filter pump owner's manual #90401 (cartridge replacement): PDF
- Embassy PoolCo, Standard thru-wall skimmer owner's guide (water level): PDF
- Pool Magic, The simple pool opening guide (pump the cover; circulate 24–48 hours): PDF
- Taylor Technologies, Top 10 pool and spa water testing tips (sample depth): taylortechnologies.com
- CDC, Home pool and hot tub water treatment and testing: cdc.gov
- Start-up doses: our engine's full plan; see methodology.