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Can you run a fish pond pump through winter?

As the seasons shift and the days shorten, both you and your pond will be bracing yourselves for colder weather. Winter brings a number of challenges to a well-stocked pond and requires a confident and organized approach to get everything through the cold months intact. Which leads us to answer the question: Can you run a fish pond pump through winter?

One of the key considerations will be whether or not your pond pump needs to stay running through Winter.

Here, we’ll take a look at how a pond pump will help your pump in Winter and if it is possible to go it alone.

The impact of Winter on your pond

Winter takes its toll on even the most well-prepared ponds, which will require plenty of TLC to keep precious plants and fish stock alive.

  • Everything gets slowed down. The effect of decreasing temperature and reduced sunlight is to drive down the biological activity that usually makes the pond ecosystem tick. Beneficial bacteria, plants, and fish enter dormancy, due to their reduced metabolic activity.

  • Cold acts as a stressor. Sustained low temperatures stress fish, reducing appetite and increasing susceptibility to disease.

  • Dead vegetation and sludge builds up. As microbial activity slows, the breakdown of fish waste and plant matter is delayed causing them to build up in the pond and affect water chemistry.

  • Icing-over of the pond surface. At temperatures of 4 degrees Celsius and below, the surface of the pond will ice over.

  • Fish enter a state of torpor, with temperature-induced dormancy and reduced feeding at the bottom of the pond.
fish pond pump through winter

Keeping a pond pump running through the Winter

If you are keeping fish in your pond you are likely to run a pond pump continually. Keeping your pump going through the Winter months will depend on conditions and is not always advantageous.

Known benefits of running a pump in Winter

One of the main benefits of running a pond pump in Winter is the prevention of ice formation, which can be fatal for fish if the pond is shallow or stepped.  Those who advocate keeping the pump running also suggest that the pump itself will be protected from becoming frozen and damaged.

Hoses and pipes which are external can also become frozen. A running pump keeps the water suitably agitated, aerated and filtered from particulates and gasses that could build up under the frozen surface.

Pond pumps in Winter can also make the circulating water slightly warmer and certainly less stagnant and will keep alive beneficial bacteria that will be relied upon to resume activity in the Spring. 

But caution may be necessary

There is often a temperature gradient in winter ponds with the deeper water shielded from harsh conditions. Though the stratification may not be particularly marked, your fish will exploit this by hanging out on the bottom of the pond to try to escape the colder temperatures at the surface.

Running a pump can mean that cold water that has been near the surface of the pond is recirculated downwards, making the overall temperature colder for your fish. 

fish pond pump through winter

Can I go without a pump through winter?

Pond owners will have their own approaches and reasons for abstaining from using a pump in the winter. There may be a reliance on the dormancy of the pond and it’s reduced metabolic demands to forgo pumping.

Also, very cold winters can freeze and crack a working pump. Even without a pump in action, filters may still need to run as a build-up of nitrogenous waste and ammonia can burn fish as they rest at the bottom.

Winterizing your pond

Ensuring your pond is properly prepared for winter will minimize the impact of the cold season on your fish and aid a smooth transition back to normal come Spring.

Whether you run your pump or not, here are some necessary steps that all pond owners should be taking to get their pond through the Winter.

1. Deadhead and clear all excess vegetation in and around your pond. A reduced bioload will keep your water clear and minimize acidity and ammonia levels.

Plants also consume vital oxygen, so reducing their consumption will benefit your fish. Before Winter sets in, plants should be cut back, and dead leaves, grass clippings and other material that could enter the pond should be thoroughly cleared. 

2. Tackle sludge. Torpid fish will want to wait out winter undisturbed at the bottom of your pond. Make sure that the sludge and waste that accumulates there is cleared, as it can release ammonia that can burn your fish and cause disease.

3. Plan to supply heat if things get too cold. Though koi and other freshwater fish are resilient, a freezing pond may be a step too far.

It is possible to heat the water with an in-line heater that works with your pond pump to stave off fluctuations in water temperature and keep your fish active.

They can be a little pricey but can achieve a stable temperature of up to 12 degrees Celsius. 

4. Throw in a tennis ball. A quick and easy way of preventing your pond from totally freezing is to add a tennis ball. It will float on the surface and prevent complete icing over.

Breaking up frozen ponds is very stressful to the fish and should be avoided. Our use a Pond De-Icer to prevent your pond freezing over in winter.

5. Stock up on winter feeds. The challenge of winter calls for a different formulation of feed for your fish, which are less active and may stop eating altogether.

Lower protein and higher fat feeds, such as wheatgerm-based feeds are better for the colder months. Garlic is also a useful ingredient, that stimulates appetite and helps to protect fish from parasites. Food should be offered twice per day.

6. Consider treatments for your fish. As Winter approaches you may want to undertake treatments for your fish that will prevent parasites, ulcers, and diseases such as fin-rot. These will be more difficult to complete in winter.

7. Test water. It can be easy to overlook but don’t let your water chemistry run away from you. Ensure you have a testing kit on-hand to keep an eye on ammonia levels, hardness and pH and be prepared to act on any problems. Try Chewy.com winter pond kit that contains all you’ll need to protect your pond and fish through winter.

Conclusion: Can you run a fish pond pump through winter?

You can definitely leave your pond pump running through the winter as the water movement is considered beneficial. But it is clear that pond pumps are only a small part of concerted work your pond will need to survive winter conditions.

As with most aspects of pond care, a proactive and holistic approach makes all the difference in keeping your pond and fish alive during the most challenging time of year.

Carl Broadbent