How to Keep a Backyard Pond From Freezing

A backyard pond in winter creates extra work if you live in northern climates. Expanding ice rips pond liners, cracks concrete and becomes a danger to fish. Even if the pond only freezes on the surface, the water below can become toxic with the buildup of fish waste and lack of fresh air. If you live in a climate where winter temperatures stay below freezing, then setting up the pond for winter becomes a yearly ritual. Fish will go into a sort of hibernation and survive very cold water temperatures, as long as the water below the surface is not frozen (above 32 degrees F) the fish will be fine.

Large ponds are less likely to freeze.
  1. Make the pond at least 4-feet deep by 4-feet wide. This helps to prevent the pond from freezing completely.

  2. Keep the water flowing with a filter, a waterfall or an air stone that emits bubbles. Moving water is less likely to freeze. All devices that keep water in motion need an electrical outlet.

  3. Install a water heater. Two heater options for ponds are an underwater heater placed in the pond or a larger heater that sits outside the pond. Heaters work using electricity or gas to heat the water, depending on the type of device used. Heaters set outside the pond remove water from the pond, heat the water and send it back. The instructions on the pond heater will need to be followed to determine what setting to use throughout the winter. When temperatures are colder you will likely have to adjust the heater setting as per the manufacturer's instructions.

  4. Use a pond de-icer. These are electrical floating heaters that create a large hole in the ice to release toxic gases and allow fresh air to enter the pond water.


  • If the pond does ice over, do not try to break the ice with an ax or other tool. The vibrations will kill the fish.
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