Guide

Natural swimming pools in winter

Our pool is in Utah, where it freezes hard every winter. It doesn't get closed and covered. It stays a pond, ducks find the open water, and a few of us swim in it through a hole in the ice. I get in five or six days a week, all year, and winter might be when I enjoy it most.

Here's how to get a natural pool through a cold winter.

October: clean it out

Cut the plants back and pull out leaf litter. Anything that rots in the pond over winter becomes algae food in spring. This is the single biggest thing you can do for clear water next year.

Keep the pump running through the first freezes

The first few winters I pulled the pump at the first sign of frost. That stalled the bacteria, and we had worse algae every spring. Now I keep it running through early freezes and pull it after a couple of days of hard freeze. The UV light and skimmer filters come out at the same time, and I drain the stock tank at the top of the waterfall so it doesn't freeze full.

Plumbing that survives ice

Every line that comes up out of the water is where freezing does its damage. Ice grips anything stiff and heaves it, and rigid PVC will eventually crack there. Use thick-walled flexible rubber line for anything that leaves the water. Route it under a dock if you can; it's hidden and shaded from UV.

If your pump sits lower than the pond's water level, put a shutoff valve on the suction line and close it whenever the pump comes out. Otherwise the pond can drain down through the line.

Spring start-up

Reinstall the pump by the end of February and dose beneficial bacteria in spring to get the filter working again. The water stays clearer if the system is running before the warm days arrive.

Swimming through the ice

We cut a hole and jump in, always with a buddy. Nobody swims alone, adults included. If you've never cold plunged, start short and never go in alone.

Plan for winter from the start

The designer builds cold-climate parts into the list for your state: flexible lines, valves and the pump setup that winters well.