{"id":1567,"date":"2026-05-15T03:14:28","date_gmt":"2026-05-15T03:14:28","guid":{"rendered":"https:\/\/aiper.com\/blogs\/?p=1567"},"modified":"2026-10-22T07:07:21","modified_gmt":"2026-10-22T07:07:21","slug":"how-to-winterize-a-pool","status":"publish","type":"post","link":"https:\/\/aiper.com\/blogs\/how-to-winterize-a-pool\/","title":{"rendered":"The Complete Guide to Winterizing Your Pool (Any Type)"},"content":{"rendered":"\n

I learned the hard way that winterizing a pool isn’t about following a checklist \u2014 it’s about understanding what $2,000 in freeze damage looks like so you don’t skip the one step that causes it. I’ve opened pools in April that were crystal clear under the cover, and I’ve opened pools that looked like swamp water with a cracked pump housing. The difference is always three or four decisions made in October.<\/p>\n\n\n\n

This guide covers every pool type \u2014 inground concrete, vinyl liner, fiberglass, above-ground, and salt water. If you have a specific inground setup with multiple skimmers, spa spillover, or complex plumbing, our inground pool winterizing guide<\/a> goes deeper on those details.<\/p>\n\n\n\n

When to Close: Watch the Water, Not the Calendar<\/h2>\n\n\n\n

The single most expensive mistake in pool winterizing is closing by the calendar. You close when water temperature stays consistently below 60\u00b0F (15\u00b0C) \u2014 not when the leaves fall, not when the neighbors close theirs, not when the pool store sends you a “winterizing sale” email.<\/p>\n\n\n\n

Close too early (warm water, above 65\u00b0F):<\/strong> algae and bacteria stay active under the cover. You’ll open to a green swamp in spring, and that algae can stain plaster and etch surfaces over five months of sitting.<\/p>\n\n\n\n

Close too late (water near freezing):<\/strong> you’re working with numb hands, racing a freeze, and one missed drain plug means a cracked pump or split pipe. Freeze damage repair starts around $500 and goes up from there.<\/p>\n\n\n\n

\"A<\/figure>\n\n\n\n

Regional rule of thumb:<\/strong><\/p>\n\n\n\n

  • Northern US \/ Canada:<\/strong> mid-September to early October \u2014 water hits 60\u00b0F earlier<\/li>
  • Mid-Atlantic \/ Midwest:<\/strong> late September to mid-October<\/li>
  • Southern US (freezing winters):<\/strong> late October to November \u2014 wait for consistent cooldown<\/li>
  • Warm climate (no hard freeze):<\/strong> you may not need to fully winterize. Run the pump during freeze warnings, keep water circulating, and you can skip most of this guide. But you still need a plan for the one cold snap each winter.<\/li><\/ul>\n\n\n\n

    What You’ll Need: Tools & Chemicals<\/h2>\n\n\n\n

    Don’t wait until closing day to realize you’re missing a $4 expansion plug. Here’s everything in one place.<\/p>\n\n\n\n

    Chemicals:<\/strong><\/p>\n\n\n\n

    • Chlorine shock (1-2 lbs per 10,000 gallons)<\/li>
    • Winter algaecide<\/strong> \u2014 not regular algaecide; winter formula is long-lasting and won’t break down under a cover<\/li>
    • pH adjuster (soda ash up, muriatic acid down \u2014 balance to 7.2\u20137.6)<\/li>
    • Alkalinity increaser (target 80\u2013120 ppm)<\/li>
    • Calcium hardness increaser (target 200\u2013400 ppm)<\/li>
    • Pool-grade antifreeze \u2014 never automotive antifreeze<\/strong> (toxic, wrong freeze range)<\/li>
    • Stain & scale preventer (especially for plaster\/vinyl pools in hard-water areas)<\/li><\/ul>\n\n\n\n

      Tools & Equipment:<\/strong><\/p>\n\n\n\n

      • Air compressor or cyclone blower (shop vac on blow mode works for small pools)<\/li>
      • Rubber expansion plugs<\/strong> \u2014 one for each return jet, plus spares. Know your pipe size (1.5″ and 2″ are most common)<\/li>
      • Gizzmo<\/strong> (skimmer freeze tube) \u2014 one per skimmer. This is not optional in freeze zones.<\/li>
      • Teflon tape \/ thread sealant for reinstalling drain plugs<\/li>
      • Submersible cover pump (solid covers only \u2014 mesh covers don’t need one)<\/li>
      • Winter cover: solid, mesh, or safety cover \u2014 see Step 7<\/em> below<\/li>
      • Air pillow<\/strong> \u2014 for above-ground pools only. Absorbs ice expansion and pushes debris outward.<\/li>
      • Cable + winch \u2014 for above-ground pool covers<\/li>
      • Plastic bag or container \u2014 for storing drain plugs, pressure gauges, salt cell indoors<\/li>
      • Silicone lubricant \u2014 for gaskets and O-rings before storage<\/li>
      • Test kit or strips \u2014 verify chemistry before closing<\/li>
      • Leaf net (optional) \u2014 place over cover if you have heavy leaf drop after closing<\/li><\/ul>\n\n\n\n

        Step 1: Balance the Chemistry<\/h2>\n\n\n\n

        Do this a week before you close<\/strong> \u2014 not on closing day. Water that sits unbalanced for five months etches plaster, corrodes metal fittings, and stains surfaces. The damage isn’t always visible in spring; sometimes a heat exchanger fails two seasons later and the tech traces it back to low pH eating through copper over the winter.<\/p>\n\n\n\n

        Your targets:<\/p>\n\n\n\n

        • pH:<\/strong> 7.2 \u2013 7.6<\/li>
        • Alkalinity:<\/strong> 80 \u2013 120 ppm<\/li>
        • Calcium hardness:<\/strong> 200 \u2013 400 ppm<\/li>
        • Chlorine:<\/strong> Shock to 10\u201312 ppm, then let it drift back to 1\u20133 ppm<\/strong> before adding winter chemicals. Algaecide added to freshly shocked water gets destroyed by the high chlorine.<\/li><\/ul>\n\n\n\n
          \"A<\/figure>\n\n\n\n

          Add winter algaecide after chlorine drops. Use a long-lasting winter formula<\/strong> \u2014 not the maintenance algaecide you use during swim season. Winter algaecide is designed to stay active for months under a cover without degrading. Follow the bottle dosage; overdosing won’t hurt but wastes money.<\/p>\n\n\n\n

          If you have metal in your water (well water, old heater), add a stain-and-scale sequestrant. Five months of sitting water gives metals plenty of time to deposit on surfaces.<\/p>\n\n\n\n

          Step 2: Clean Everything Before You Cover It<\/h2>\n\n\n\n

          Anything you leave in the pool \u2014 leaves, dirt, algae spores, dead bugs \u2014 becomes spring sludge. The cleaner the pool on closing day, the clearer it’ll be when you pull the cover.<\/p>\n\n\n\n

          • Brush walls, floor, steps, and behind ladders where algae likes to hide<\/li>
          • Vacuum thoroughly \u2014 manual or robotic, just get the debris off the floor<\/li>
          • Empty skimmer and pump baskets<\/li>
          • Backwash the filter (sand\/DE) or pull and hose down cartridges<\/li>
          • Remove ladders, diving boards, ropes, floats, and toys \u2014 they’ll crack or stain over winter<\/li><\/ul>\n\n\n\n

            Running a robotic pool cleaner a day or two before closing takes this step off your plate \u2014 it scrubs the floor and waterline while you handle the chemicals and equipment. If you don’t own one, a manual pole brush and vacuum work fine; it just adds an hour to your closing day.<\/p>\n\n\n\n

            Step 3: Lower the Water Level<\/h2>\n\n\n\n

            How much you drain depends on your pool type and cover:<\/p>\n\n\n\n

            Water level guidelines by pool type:<\/strong><\/p>\n\n\n\n

            \u2022 Inground, mesh cover:<\/strong> 4\u20136″ below skimmer \u2014 rain and snow pass through mesh, water level rises over winter<\/p>\n\n\n\n

            \u2022 Inground, solid cover:<\/strong> Just below tile line \u2014 solid cover blocks precipitation, level stays roughly stable<\/p>\n\n\n\n

            \u2022 Vinyl liner (any):<\/strong> No more than 6″ below normal; keep as high as possible \u2014 over-draining causes liner to shrink, tear, or pull from track<\/p>\n\n\n\n

            \u2022 Fiberglass:<\/strong> Keep water high \u2014 no more than 6″ below normal \u2014 low water + high groundwater can flex or float the shell<\/p>\n\n\n\n

            \u2022 Above-ground:<\/strong> Below skimmer OR use skimmer plate to keep full \u2014 air pillow under cover absorbs ice pressure<\/p>\n\n\n\n

            The vinyl liner warning is serious.<\/strong> Liners shrink when exposed to cold air without water pressure behind them. If the liner pulls away from the coping, you’re looking at a replacement \u2014 $2,500 to $4,500 with labor. I’ve seen it happen to a neighbor who drained 18 inches because “the internet said to drain below the returns.” Keep that water high.<\/p>\n\n\n\n

            Step 4: Drain & Winterize the Equipment Pad<\/h2>\n\n\n\n

            This is where most DIY closings go right or wrong. Water anywhere in the system = freeze damage. No exceptions.<\/p>\n\n\n\n

            Pump:<\/strong> Remove both drain plugs (there are usually two \u2014 one on the housing, one on the volute). Store them in the pump basket so you can actually find them in April. Tip the pump if possible to let any trapped water drain.<\/p>\n\n\n\n

            Filter:<\/strong><\/p>\n\n\n\n

            • Sand filter:<\/strong> Backwash thoroughly, drain the tank via the bottom drain plug, set multiport valve to “Winterize” or a position between settings (so the gasket isn’t compressed all winter). Leave the drain cap off.<\/li>
            • Cartridge filter:<\/strong> Remove cartridge, hose it down, let it dry, store indoors. Drain the tank. Leave the band clamp loose \u2014 a tight clamp all winter can seize.<\/li>
            • DE filter:<\/strong> Full breakdown and rinse. Remove grids, hose each one, inspect for tears. Reassemble loose or store grids indoors. Drain tank completely.<\/li><\/ul>\n\n\n\n

              Heater:<\/strong> Drain completely via the drain plug. If your heater has a pressure switch, blow through that line too. Heater replacement runs $3,000+ \u2014 the five minutes you spend here are the best return on time in the entire process.<\/p>\n\n\n\n

              Chlorinator \/ chemical feeder:<\/strong> Empty it. Remove any remaining tablets. Rinse. Drain. Chlorine tabs sitting in a closed feeder all winter produce corrosive gas that eats seals and O-rings.<\/p>\n\n\n\n

              Pressure gauges:<\/strong> Take them off and store indoors. They freeze and crack every time. $15 part, but annoying to discover in spring when you’re ready to fire up the system.<\/p>\n\n\n\n

              Step 5: Blow Out the Lines<\/h2>\n\n\n\n

              Every pipe that holds water needs to be emptied. That means skimmer lines, return lines, main drain, dedicated cleaner suction lines, waterfall lines, spa jets \u2014 anything wet.<\/p>\n\n\n\n

              What you need:<\/strong> A cyclone blower is the gold standard ($300\u2013400 if you buy one; many pool stores rent them). An air compressor works for smaller systems \u2014 set it to 20\u201330 PSI, no higher, or you risk blowing fittings apart. A shop vac on blow mode handles small above-ground pools but may not have enough volume for long inground runs.<\/p>\n\n\n\n

              The process:<\/strong><\/p>\n\n\n\n

              1.<\/strong> Connect the blower to the skimmer line \u2014 use a threaded adapter, not duct tape. It will pop off at the worst moment.<\/p>\n\n\n\n

              2.<\/strong> Blow until you see steady bubbles from each return jet in the pool.<\/p>\n\n\n\n

              3.<\/strong> While air is still blowing, plug each return jet with a rubber expansion plug. Tighten until snug only \u2014 overtightening can crack the fitting.<\/p>\n\n\n\n

              4.<\/strong> Shut off the blower, then quickly plug the skimmer line at the equipment pad.<\/p>\n\n\n\n

              5.<\/strong> Pour pool-grade antifreeze into each line through the skimmer and returns \u2014 about 1 gallon per 10 feet of 1.5-inch pipe. The antifreeze displaces any residual water and prevents freeze cracks where the blower couldn’t clear everything.<\/p>\n\n\n\n

              6.<\/strong> Blow the main drain line until a rush of bubbles comes from the deep-end drain. Close the valve immediately \u2014 the air lock method keeps the vertical water column below the freeze line stable while the air gap at the top protects the exposed section.<\/p>\n\n\n\n

              Skimmer protection:<\/strong> Install a Gizzmo (threaded plastic tube) in each skimmer. The Gizzmo compresses if ice forms inside the skimmer housing, absorbing the expansion instead of cracking the plastic. Then stuff the skimmer with a piece of pool noodle or foam rope as backup. Skimmer replacement on a gunite pool is a $1,000+ concrete-cutting job. Don’t skip this.<\/p>\n\n\n\n

              Step 6: Plug, Protect & Secure<\/h2>\n\n\n\n

              Double-check every plug is tight. Walk the pool and press on each return plug \u2014 they should be firm with no give. A plug that pops out in January means that line freezes.<\/p>\n\n\n\n

              Store all loose items: ladders, handrails, diving board, slide, ropes, floats, solar cover and reel. Anything plastic left outside for five months of freeze-thaw cycling will be brittle or cracked by spring.<\/p>\n\n\n\n

              For above-ground pools: position the air pillow in the center of the pool before pulling the cover over. The pillow absorbs ice expansion and pushes rain\/snow\/debris toward the edges where the cover drains. Secure the cover with the cable and winch around the top rail \u2014 tight enough that wind can’t get under it, not so tight that the cover tears when snow loads it.<\/p>\n\n\n\n

              Step 7: Choose & Install the Right Cover<\/h2>\n\n\n\n

              Your cover determines what you’ll find in spring.<\/p>\n\n\n\n

              Cover type comparison:<\/strong><\/p>\n\n\n\n

              \u2022 Mesh safety cover:<\/strong> Spring water is green and needs work, but winter maintenance is almost none. Cost: $1,200\u20133,000. Lifespan: 12\u201315+ years.<\/p>\n\n\n\n

              \u2022 Solid safety cover:<\/strong> Spring water is clear, minimal shock needed. Pump water off top periodically. Cost: $1,500\u20133,500. Lifespan: 10\u201315 years.<\/p>\n\n\n\n

              \u2022 Solid tarp cover (water bags):<\/strong> Spring water is clear. Frequent pumping needed; water bags leak or freeze. Cost: $100\u2013300. Lifespan: 2\u20135 years.<\/p>\n\n\n\n

              \u2022 Above-ground cover (cable + winch):<\/strong> Spring water depends on mesh\/solid. Debris removal from top needed. Cost: $50\u2013150. Lifespan: 3\u20137 years.<\/p>\n\n\n\n

              \"A<\/figure>\n\n\n\n

              Safety covers are the standard for a reason.<\/strong> An ASTM-rated safety cover holds the weight of a person, a pet, or a deer that wanders onto it. If you have kids or animals anywhere near your property, a tarp-and-water-bag setup is not enough. I don’t say this to scare you \u2014 I say it because I’ve pulled a neighbor’s dog out of a pool after a tarp cover gave way. It’s not something you want to experience.<\/p>\n\n\n\n

              For solid safety covers on inground pools: install the cover pump in the center and run the discharge hose to a spot that drains away from the pool. Check after heavy rain or snowmelt \u2014 if the pump intake gets blocked by leaves, water accumulates and the whole cover sinks, pulling on the anchors.<\/p>\n\n\n\n

              Interactive Winter Closing Checklist<\/h2>\n\n\n\n

              Click each step as you complete it. Your progress is saved \u2014 come back anytime to pick up where you left off.<\/p>\n\n\n\n