How to Winterize Pool Equipment Before Freeze Season

Water expands by roughly 9% when it freezes, and pool equipment isn't built to absorb that. A pump housing, a heater's heat exchanger, or a run of PVC plumbing can crack from a single hard freeze, and you often won't know it happened until you fire everything up in spring and find a slow leak or a dead pump. Winterizing is really just freeze-proofing: getting standing water out of anything that could split when it turns to ice.

First, figure out how much winterizing you actually need

Not every pool needs the full shutdown. How far you go depends on how often and how hard your area actually freezes, not just whether the calendar says winter.

If you're not sure which category you're in, err toward more protection rather than less. A pump or heater is a lot more expensive to replace than an afternoon of draining lines is to spend.

Draining the pump and filter

The pump and filter hold the most standing water on your equipment pad, and they're usually the first things to crack in a freeze. Always shut off power at the breaker before touching anything, not just at the timer or automation panel.

• Turn off power to the pump at the breaker, then remove the drain plugs on the pump housing (usually one or two, on the bottom or side of the pump body) and let it fully drain.
• For a sand or DE filter, open the drain plug at the bottom of the tank and let it empty. Backwash first if it's due, then leave the multiport valve or drain cap slightly open so trapped water and air can escape rather than freeze under pressure.
• For a cartridge filter, remove the cartridge, hose it off, and store it indoors somewhere dry. Drain the empty filter housing the same way you would a sand or DE tank.
• Leave pump and filter drain plugs out (or loosely reinstalled) for the winter so any residual water has somewhere to go instead of collecting and freezing.

Protecting the heater

Heaters are one of the more expensive things on the pad to replace, and their heat exchangers are especially vulnerable because they're full of narrow internal passages that trap water. If you're not planning to run the heater over winter, drain it completely: most gas and heat pump models have a drain plug (sometimes more than one) at the base of the heat exchanger. Open it and let gravity do the work, then consider using a shop vac to blow out any water pooled in the internal coils. If you're at all unsure where your model's drain points are, the owner's manual or a quick call to the manufacturer is worth it, a missed drain plug is a common way heaters crack over winter.

Clearing the plumbing lines

This is the step people skip and regret. Underground and above-ground PVC lines can hold water even after the pad equipment is drained, and buried lines are the hardest (and most expensive) place to discover a crack.

• Use a shop vac at each skimmer and return line to blow remaining water back toward the pool, working one line at a time.
• Once a line is cleared, plug it. Skimmers typically take a threaded winterizing plug; return lines often use a rubber expansion plug (sometimes called a "gizmo" or winterizing plug) that seals against the pipe wall when tightened.
• In colder climates, many pool owners add pool-specific antifreeze (propylene glycol, not automotive antifreeze) to lines that can't be fully blown dry, as extra insurance against any water left behind.
• Lower the water level below the skimmer opening if you're closing the pool for the season, so ice forming at the surface has room to expand without pushing against the skimmer body.

Don't skip the water chemistry before you close up

A pool that's balanced and reasonably clean before it's covered stays that way far better than one that's closed in whatever state it happened to be in. Before you close for the season, get pH into the 7.4-7.6 ideal range, total alkalinity into 80-120 ppm, and give the water a shock dose so it's not sitting all winter with depleted sanitizer. None of this needs to be perfect, it just needs to be in range so algae and scale have a harder time getting started under the cover. Skimmer's dosing calculators can work out how much of each chemical to add based on your pool's volume, and logging that last test before closing gives you an easy baseline to compare against when you reopen.

What to check when you reopen

Before you restore power and start the pump in spring, do a quick visual pass: check that drain plugs are back in and hand-tight, look for any obvious cracks in the pump housing or filter tank that weren't there in fall, and confirm the winterizing plugs are still seated in the skimmer and return lines. Prime the pump before running it for the first time so it doesn't run dry. If you kept a maintenance log of what you drained and where the plugs went, reopening takes a fraction of the time, which is exactly the kind of detail Skimmer's equipment tracking is meant to hold onto for you across seasons.