Winterizing a pool is the most important maintenance event of the year in any climate that sees freezing temperatures. A pool that is closed correctly opens clean in spring with no equipment damage. A pool that is closed incorrectly opens with cracked plumbing, ruined pumps, ice damage to skimmers, and a green water column that takes weeks to clear.
Winterizing a pool is the most important maintenance event of the year in any climate that sees freezing temperatures. A pool that is closed correctly opens clean in spring with no equipment damage. A pool that is closed incorrectly opens with cracked plumbing, ruined pumps, ice damage to skimmers, and a green water column that takes weeks to clear.
This guide is the complete WETYR Pools reference on pool winterization. The process is mechanical, chemical, and procedural; every step exists for a reason, and skipping any one of them is the most common cause of spring-opening problems.
If you would rather have a professional handle it, WETYR Pools offers full winterization service across our maintenance markets. We blow out the lines with a commercial blower, add the right antifreeze, set the cover, and document the entire closing so the spring opening is straightforward. Use the form on this page or email [email protected].
Close the pool when daytime water temperature is consistently below 65 degrees Fahrenheit, usually after the first cold snap but before the first hard freeze. In the northern US that is mid October to early November. In the transition belt (Mid-Atlantic, Midwest, Mountain West) it is late October to mid November. In the upper South it may be late November to early December.
Closing too early invites algae blooms during the still-warm transition weeks; closing too late risks freeze damage if a hard freeze hits before the lines are blown out. Watch the 10-day forecast for the first sustained sub-32 night and close 5 to 7 days before that.
Pools in zones that never freeze (south Florida, south Texas, southern California, the Gulf and lower Sun Belt) do not need full winterization. Those pools transition to a winter maintenance schedule with reduced pump runtime and seasonal chemistry.
Winterizing chemicals: pH up and pH down, alkalinity increaser, calcium hypochlorite shock, winter algaecide (60 percent polyquat is the gold standard), stain and scale preventer, and pool antifreeze (RV/marine antifreeze, never automotive ethylene glycol).
Equipment: a powerful air blower (a commercial blower or a wet/dry shop vac on reverse), winterizing skimmer plugs and return plugs, a Gizzmo for the skimmer, a winter cover (solid safety cover, mesh safety cover, or standard water-bag cover), water bags or cover anchors, an air pillow for above-ground pools, and a pool cover pump.
The cheapest piece of advice in this entire guide: invest in a real blower (or rent one). Lung power and shop vacs do not move enough air to clear long underground plumbing runs. Lines left with water in them are the single biggest cause of winter equipment failure.
Above-ground pools follow the same chemistry and cover steps but require an air pillow under the cover to absorb ice expansion, removal and indoor storage of the pump and filter, and lower water below the skimmer and returns (or installation of a skimmer plate). Hoses come off and drain dry; valves get blown out with a shop vac.
Above-ground pools in mild climates can sometimes stay open with reduced runtime. In freezing climates, full closing is the right move; the heave from a winter freeze can damage walls and liners if water is left at normal level under a cover.
Brush the pool, vacuum, skim debris, and clean the filter. Adjust pH to 7.4 to 7.6, total alkalinity to 80 to 120 ppm, and calcium hardness to 200 to 400 ppm. Test cyanuric acid; if over 80 ppm, partial drain may be appropriate. These steps a week ahead let chemistry stabilize before the winter chlorine dose.
Add a heavy shock dose (double the normal weekly shock) to give chlorine a reserve heading into winter. Run the pump overnight to circulate. Test the next day to confirm free chlorine is 5+ ppm. Then add the winter algaecide (polyquat 60), stain and scale preventer, and metal sequestrant if your water has iron, copper, or manganese.
For pools with solid safety covers: lower the water 4 to 6 inches below the skimmer. For pools with mesh safety covers in freeze climates: lower below the returns (typically 12 to 18 inches below skimmer). For pools with standard water-bag covers: 6 to 12 inches below the skimmer. Use a submersible pump; do not drain through the pump (the pump is not designed to run dry).
Remove the drain plug from the pump and filter. Connect the blower to the skimmer or to a fitting at the pump and force air through each line until bubbles in the pool stop and only steady air comes out. Cap the line at the pool end with a winterizing plug while the blower is running, so air pressure stays in the line. Do this for every return, each skimmer, the main drain, the spa lines if connected, and the cleaner line. Lines not blown out clear are at high risk of freeze damage.
After blowing each line, pour pool-grade antifreeze (propylene glycol, the same chemistry as RV/marine antifreeze) into the line at the equipment pad before plugging. Use about a gallon per 10 feet of line. Antifreeze fills any low spots where blown-out lines still hold a teaspoon of water that could freeze and split the pipe. Never use automotive antifreeze (ethylene glycol); it is toxic and not designed for potable plumbing.
Remove the drain plug from the pump basket. Remove the drain plug at the bottom of the filter housing. Open the multiport valve to the winterize position (if equipped). Remove and store the pressure gauge if it is glycerin-filled (freezing damages it). Disconnect and drain the heater (gas heaters have a specific procedure; heat pumps have another; consult the manual). Bring all electronic components inside if practical.
Install a threaded winter plug in every return jet. Place a Gizzmo (an expanding plastic tube) in the skimmer; as water freezes, ice expands into the Gizzmo instead of cracking the skimmer wall. For pools without Gizzmos: fill the skimmer with empty milk jugs or foam to absorb ice expansion. Either method prevents the most common winter freeze failure: a cracked skimmer.
For safety covers: stretch the cover taut and secure all anchors. For water-bag covers: fold the leading edge under, lay the cover edge-to-edge across the pool, then fill water bags (do not over-fill; they need to flex). For above-ground pools: install the air pillow, then the cover, then the cable and winch around the perimeter. Inspect the cover for tears before installation; a torn cover is a winter algae source.
Photograph every drain plug, valve position, and disconnected component. Bag the drain plugs, pressure gauge, and small parts together; label and store indoors. Spring opening goes 3x faster when the closing is documented. WETYR Pools provides a closing report with photos, plug inventory, and a spring-opening checklist.
DIY winterization is reasonable for owners who have closed pools before, have the right blower, and live in zones with shorter freeze seasons (USDA zones 7 and 8). It typically takes 3 to 5 hours plus a week of chemistry prep.
Call a pro when: you are in zones 6 and colder (deep freeze risk is unforgiving of mistakes), you do not own a real blower, your pool has complex plumbing with auto-fillers, water features, or in-floor cleaners, or you are not 100 percent confident on the line layout. A failed closing repair (cracked underground pipe, blown skimmer) costs $500 to $5,000+, much more than a professional winterization.
WETYR Pools provides full winterization across our maintenance markets. A professional close uses a commercial blower, pool-grade antifreeze, the right Gizzmo/plug inventory for your pool, and an experienced eye for the line layout. The closing is documented with photos so spring opening is fast and traceable.
Cost for professional winterization ranges from about $250 for a small simple inground pool with a basic cover, $300 to $500 for a typical residential inground with a safety cover, and $500 to $1,200 for pools with spas, water features, in-floor cleaners, or complex equipment. Bundling with spring opening or a year-round maintenance plan typically reduces both prices.
The top winter failures: water left in lines (freeze and crack), skimmer cracked from no Gizzmo, cover collapse from no cover pump, mid-winter algae from low chlorine or no algaecide, and stains from minerals left in the water without a sequestrant.
Each one is preventable: blow lines properly and add antifreeze, use a Gizzmo or fill skimmer with floats, run a cover pump after every storm, dose polyquat 60 algaecide at close, and add a metal sequestrant if your fill water tests positive for iron or copper. WETYR Pools' winterization service handles all of this on every close.
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20 of the most-asked questions on Reddit, Quora, and pool owner forums, answered by the WETYR Pools team.
Close when daytime water temperature is consistently below 65 degrees Fahrenheit. In the northern US that is mid October to early November. In the Mid-Atlantic and Midwest it is late October to mid November. Watch the forecast and close 5 to 7 days before the first sustained sub-32 night.
Generally no for south Florida, south Texas, and the lower Sun Belt where freezes are rare and brief. Pools transition to a winter maintenance schedule with reduced pump runtime. Northern Florida and the I-10 corridor occasionally see hard freezes; for those areas, freeze protection (running the pump during a freeze warning) is the standard approach.
DIY: $80 to $200 in chemicals plus optional blower rental. Professional service: $250 to $500 for a typical inground pool, $500 to $1,200 for complex pools. Cracked pipe repair after a failed close runs $500 to $5,000+.
Not safely in any zone that sees a hard freeze. A blower clears most water but leaves a teaspoon or two in low spots; that small amount expands enough to crack PVC. Pool-grade antifreeze is cheap insurance. Use propylene glycol (RV/marine), never automotive ethylene glycol.
A real shop blower or commercial pool blower moves enough air. A standard shop vac on reverse is marginal; it works for short runs but not for long underground plumbing. Renting a 2 to 3 hp blower for a day is the right answer for DIY closes.
No. A drained pool can pop out of the ground from groundwater pressure, especially gunite/concrete pools and fiberglass pools. Lower water 4 to 18 inches below the skimmer depending on cover type, not to empty. Full drains are only for resurfacing or repair, not for winter.
A Gizzmo is an expanding plastic tube that goes in the skimmer to absorb ice expansion and prevent the skimmer from cracking. Yes, you need one (or a substitute like a filled empty bottle); skimmer cracking from ice is a top-3 winter failure.
Not recommended. A tarp is not engineered for pool use, sags from rain and snow load, traps debris, and can collapse into the pool. A proper winter cover (water-bag or safety cover) is the right answer.
Safety covers anchor to the deck with springs and straps, support an adult's weight, and last 7 to 15 years. Water-bag covers are tarps held down by water bags around the perimeter, cheaper at $200 to $400, last 2 to 4 years, and do not support weight (a child or pet falling onto a water-bag cover can drown). Safety covers are the better answer for any home with kids, pets, or wildlife.
Air pressure stays up after the line is plugged at the pool end. If air keeps escaping into the pool when blowing, plug the pool-end fitting first, then watch the blower pressure; pressure that holds means the line is clear (or sealed). Pour antifreeze into each line at the equipment pad after blowing as a final insurance step.
No. Drain gas heaters per the manual (there are usually 2 to 4 drain plugs on the heat exchanger and the pressure switch). Drain heat pumps by following their winterization procedure (some use compressed air through specific ports). Frozen heaters crack heat exchangers; replacement costs $1,500 to $4,000.
Yes. WETYR Pools provides full pool winterization across our maintenance markets as part of seasonal service. Bundled spring opening plus winter closing is the most popular service combination. Request a quote through the form on this page or email [email protected].
Top failures: cracked underground pipes ($500 to $5,000+), cracked skimmer ($300 to $1,500), cracked filter or pump housing ($200 to $1,500), heater heat exchanger damage ($1,500 to $4,000), green spring water (weeks of chemistry recovery), and torn cover from neglected cover pump (replacement $200 to $3,500).
Yes. Run the pump continuously through the freeze. Moving water does not freeze at the same temperature as still water, and circulation prevents ice from forming in the lines. This is the standard freeze protection in southern climates that do not fully winterize.
Yes, with one addition: remove the salt cell, clean it, and store it indoors. Cap the open cell housing with the dummy cell that came with the system. Salt water freezing in a cell can crack the cell housing; replacement cells cost $400 to $1,200.
Open when daytime water temperature is consistently above 60 degrees Fahrenheit and you are 10 days from the last freeze risk. In most US zones that is mid March to mid April. Opening early invites algae blooms during cold-to-warm transition; opening late means a heavier green pool recovery.
Yes. Use a cover pump to remove standing water after every storm. Standing water over 1 to 2 inches stresses the cover, can pull it into the pool, and breeds algae and mosquitoes. An automatic cover pump (about $80 to $200) handles this without daily attention.
Only the top 6 to 18 inches will freeze in even the coldest zones. The body of water below stays liquid. The cover and lower water level let ice expand without damaging the structure. Plumbing is the freeze risk, not the pool itself.
Run the pump 24 hours through the freeze. Open the air relief valves. Wrap exposed plumbing in insulation. Be prepared for repair costs if it freezes hard. As soon as the freeze passes, do a proper close. WETYR Pools provides emergency winterization in our markets.
Yes, if you have a real blower, follow this guide step by step, and document everything. Many homeowners do their first close with a pro to learn the layout and shortcuts, then DIY in subsequent years. WETYR Pools offers a learning service where we close with the homeowner watching for $50 to $100 above standard winterization cost.
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