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How to Winterize an In-Ground Pool (and Tuck It In for Its Long Winter Nap)

This entry was posted on by mpsblog.

Well, it happened. The floaties are deflated, the sunscreen has been demoted to the back of the closet, and your pool is giving you that look that says, "So... are we doing this or not?"

Yes, it's closing time. Your pool is about to go into hibernation, and like any good hibernating creature, it needs some prep first. Skip it, and freezing water can crack your pipes, pump, filter and heater. (Nothing says "Happy Spring!" like a cracked filter tank.)

The good news? It's a checklist, not rocket science. Here's how to do it, using the steps published by the equipment makers.

Quick heads-up: Hayward recommends hiring a reputable pool professional to close your pool, and Pentair also suggests booking a pro. If you'd rather DIY, follow the steps below and your own equipment manuals, since those always win for your specific model.

Who needs to winterize?

Per Pentair: if you get a consistent amount of snow, sleet, or temperatures around or below 32°F, you need to winterize. If you're reading this while wearing a jacket, that's probably you.

Step-by-step: closing your in-ground pool

1. Balance the water

The week you close, get your water into these ranges (Hayward):

  1. pH: 7.2–7.8
  2. Total alkalinity: 80–120 ppm
  3. Calcium hardness: 180–220 ppm

Balanced water helps you avoid algae blooms and scaling when the cover comes off in spring. Think of it as packing your pool a healthy lunch before a very long trip.

2. Shock first, then add winter algaecide

  1. Shock the pool following the shock manufacturer's package directions.
  2. Wait until chlorine drops to 1.0–3.0 ppm.
  3. Then add winter algaecide.

Never add shock and algaecide at the same time (Hayward).

3. Clean the pool

  1. Brush the walls and vacuum the pool.
  2. Really dirty or algae-ish? Hayward says vacuum to waste: set the multiport valve to drain/waste so the gunk skips the filter and goes out the backwash line.
  3. Goal: as clean and clear as possible before the cover goes on. Anything you leave behind spends all winter getting... let's say "more interesting."

4. Pull out the accessories

Remove skimmer baskets, wall fittings, cleaners, solar blankets and ladders, and store them. Don't coil cleaner hoses tightly (Hayward). Pentair also says to remove booster pumps and pool cleaners.

5. Lower the water level

Use the filter pump or a submersible pump (Hayward):

  1. Mesh cover: lower water 12"–18" below the skimmer.
  2. Solid, floating cover: lower water 3"–6" below the tile.
  3. Some covers don't need the water lowered at all, so check your cover's manual.

Do not empty the pool! Pentair warns that freezing, expanding soil can push an empty pool out of the ground. Your pool needs that water weight to stay put. Hibernation, not evacuation.

6. Blow out and plug the lines

For in-ground pools, Hayward says to blow out the lines from the skimmer, through the equipment, and back to the pool, then plug the lines at the pool with expansion plugs. Pentair's guide adds:

  1. Blow air through the suction (skimmer) lines.
  2. Blow out the returns until air bubbles come out of the return jets, then tightly plug each fitting below the water line.
  3. Main drain: when you see bubbles at the drain, plug the pipe on your end or close the gate valve. This creates an "air lock" so pool water can't get back into that line.
  4. A gizmo or plug in the skimmer helps protect pipes from frozen water (Pentair).
  5. Didn't blow the lines? Hayward says to add swimming pool antifreeze to the lines, following the antifreeze maker's directions.

7. Drain the pump, filter and heater

  1. Turn off the breakers to your pool equipment first.
  2. Open the filter air relief, then use the drain plugs to drain your pump, filter, heater and chlorinator. All water must be drained or blown out so nothing freezes and cracks (Hayward).
  3. Remove and thoroughly clean D.E. filter grids and cartridges.
  4. If possible, store the pump and filter indoors. If not, blow out leftover water with a shop vac or compressor (Hayward).
  5. Heater: drain it completely, remove the drain plugs, and make sure no water is standing inside (Pentair). Gas heater with cast iron plugs? Lubricate the threads or leave the plugs in after draining to prevent rust (Hayward).
  6. Pro tip from Pentair: stash the drain plugs in the pump basket so you can actually find them in spring.

8. Lube the O-rings

Fall is a good time to lubricate the pump lid O-rings, plus the O-rings on a push-pull (slide) valve if your filter has one (Hayward). Cracked or flattened? Swap it now while you're thinking about it.

9. Remove and store the salt cell

Salt pool folks, this one's yours. Hayward's AquaRite manual says the cell and flow switch will be damaged by freezing water, so drain all water from the pump, filter and lines before any freeze. Hayward's salt-pool winterizing guide then says:

  1. Turn the power off and unplug the cell.
  2. Remove the cell if you can, clean it, dry it, and store it somewhere dry and frost-free.
  3. If your cell is fixed in place and can't come out, make sure it's completely emptied and covered.

The AquaRite manual notes the electronic control can handle winter weather and should not be removed.

10. Cover it up

  1. A tight-fitting cover is essential. Hayward calls a mesh safety cover the most desirable and safer choice.
  2. Solid covers need a cover pump or siphon to get rid of rainwater and snow melt (Hayward).

Then step back and admire your work. Your pool is officially hibernating. Shhh.

⚠️ Safety box

  • Power off first. Turn off all pool equipment breakers before draining or opening anything.
  • Chemicals: follow every package's directions. Never add shock and algaecide together.
  • Don't drain the pool empty. It can lift out of the ground.
  • Filter: when draining, open the filter's air relief and remove its drain plug (Hayward). Follow your equipment manuals.
  • When in doubt, both Hayward and Pentair recommend a pool professional.

Shop winterizing supplies

Everything below ships to your door. We're online-only, with 30-day returns. Check sizes and fit against your equipment before ordering.

Plugs and freeze protection

Pump drain plugs and O-rings

Water balance and winter chemicals

Covers and cover care

See you in spring

That's it. Summer's officially over, and your pool is snoozing safely. Need plugs, O-rings, covers or chemicals? Shop online at majorpoolsupplies.com or send us a message. We ship right to your door, with 30-day returns.

This article is general information based on published manufacturer guidance and is not a substitute for your equipment's instructions.

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