Protecting your pool from a freeze

About 15 minutes, or an hour if you drain the equipment

1. 1Run the pump continuouslySet the pump to run without stopping until the temperature is back above freezing — not on its usual schedule, and not just overnight. If you have a variable-speed pump, a low speed is fine and cheaper.Moving water does not freeze at the temperatures most pools ever see. This one step carries a typical pool through a normal cold snap on its own.
2. 2Drop the water below the returnsLower the water level until it sits below the return fittings on the pool wall — the jets the water comes back in through.Ice expanding at the waterline is what cracks tile, skimmers and return fittings. Below the returns, it has somewhere to go.
3. 3Open the valvesOpen every valve on the equipment pad so water can move rather than sit trapped between two closed points.A closed valve turns a length of pipe into a sealed container. Freezing water in a sealed container splits it.
4. 4Drain the pump, filter and heaterIf the freeze will last more than a night or you cannot keep the pump running, pull the drain plugs on the pump and filter, and drain the heater. Keep the plugs somewhere you will find them in spring.This is the one that actually protects the expensive parts. Trapped water inside the equipment — not the cold itself — is what breaks pumps, filters and heaters.

These four steps cover an overnight freeze or a cold snap, which is what most pools face. A sustained hard winter needs a full close instead — blowing the lines out and plugging them — and that is the closing checklist, not this page.

When the cold passes, put the plugs back, bring the water level up to mid-skimmer, and log a water test. A freeze does not change your chemistry much, but a few days of unusual pump running can.

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