Do Pond Pumps Need to Run All Winter?
The first hard frost arrives and the pond goes quiet. The pump is still running, but is it doing any good? Or is it just adding to your electric bill and risking a frozen pipe?
The answer depends on what lives in your pond and how cold your winter gets.
Here is how to decide.
Do Pond Pumps Need to Run All Winter?
Not always. If your pond has fish, running the pump on a low flow through winter keeps the water moving and the filter bacteria alive. If your pond has no fish, you can switch the pump off, lift it out and store it until spring. Either way, the pump must be protected from freezing. Ice can crack a pump housing and split pipework.
What Should You Do With Your Pond Pump in Winter?
If you have fish
Fish slow right down once the water drops below about 10°C. They stop feeding and spend most of the winter near the bottom. They still need oxygen, though, and the water still needs to stay clean.
A pump and filter running gently keeps the water moving and helps it take on oxygen at the surface. The beneficial bacteria in your filter also survive better when water keeps passing through. Switch everything off and those bacteria can die back. The pond may then struggle to clear itself in spring.
Do not run the pump at full power. Strong flow pulls heat out of the water and can chill the deeper layer where fish shelter. Turn the flow down if your pump allows it. Raise the pump off the pond floor on a brick or a plant pot so it does not stir up the bottom layer.
How cold is too cold?
In a mild spell, with the water above freezing, a running pump is fine. In a hard freeze, ice can form around the pump and the outlet pipe. If the flow stops, the pump can overheat or the pipe can split. A deeper pond holds its heat better and is safer to leave running. A shallow pond that could freeze solid is a different matter. In that case, lift the pump out.
Turn off waterfalls and fountains
Falling water cools a pond quickly. Spray can also freeze on the edges and lead to water loss. Switch the feature off for winter. Let the pump feed the filter only, or swap to a smaller pump if yours is too powerful on its own.
If you have no fish
A wildlife pond or a plant only pond does not need a pump over winter. Switch it off, lift it out and store it. Leaving a pump in a freezing pond puts it at risk for no real benefit.
Keep a gap in the ice
A layer of ice is not a problem on its own. A sealed pond is. Gases from rotting leaves and fish waste build up under the ice, and fresh oxygen cannot get in. Keep at least a small hole open.
A floating pond heater does this well and uses little power, because it only warms a small area. An air pump with an air stone also works. It oxygenates the water and keeps the surface moving. Never smash the ice with a hammer. The shock can harm fish.
Storing the pump
Lift the pump out before the hard frosts if you are switching it off. Disconnect it and keep it in a bucket of water in a frost free shed or garage. Keeping it wet stops the seals drying out. Drain external pumps and pipework completely, as trapped water will freeze and split them.
Check before the cold sets in
Look over the cable for cracks or wear. Make sure the power supply runs through an RCD ( Residual Current Device). Clear leaves from the pump inlet and filter so the flow does not drop away when you are not looking.
Need Help Getting Your Pond Ready for Winter?
Some of our pond accessories are available on our eBay store. If there is something you cannot see, let us know.
Get in touch if you need any help choosing the right equipment for your pond.
Pond Pump Winter FAQs
How much does it cost to run a pond pump in winter?
Check the wattage on the pump label. Multiply it by the hours the pump runs, divide by 1000 to get kilowatt hours, then multiply by your unit rate. A small pump on a low flow costs far less than most people expect.
When should I restart my pond pump in spring?
Wait until the frosts have passed and the water is steadily above about 10°C. Refit the pump, check the cable and seals, then start it gently. Test the water, as the filter can take a few weeks to settle. Feed fish lightly at first.
Can a pump alone stop my pond freezing?
No. A pump moves water but adds no heat, and strong flow can cool the pond faster. To keep a gap in the ice, use a heater or an air pump.
