If you ask me, I’ll say don’t run your pond all winter. However, a lot of pond owners do keep them running and are confident in doing so, and to them, I say do whatever has worked for you. But if there are any problems, it’s not on me. 🙂 Now let’s talk about the reasons why shutting the pond down for winter is a good idea…
Things that could happen
1). Don’t run your pond all winter, the risk of ice forming and damaging or even breaking pipes, valves, UV lights or pumps is very high. Keeping the water running at a high volume helps, but during extreme cold ice can slowly start to form and build up. External pumps may start to build up ice in the traps (strainer baskets) and as the ice builds up, the water flow slows down, until it stops and then it may lead to everything else freezing up. Having to fix things when it’s freezing cold outside is not fun. And having to replace broken pumps or UV lights can also be very expensive. If a pipe should crack, and a big leak occurs, you could end up with a pond drained down, fish in distress, and with a foot of snow covering the pond and frozen hoses you’ll have quite a mess on your hands.
2). With the water running down a waterfall, and ice starts to form on the rocks, that ice grows bigger and bigger as more water continues to flow over it. The ice could continue to expand to a point where the water starts to run over the side of the waterfall and out of the pond causing a major leak. The same holds true with a stream bed, the ice can build up forming a dam where the water is blocked from continuing to flow down the stream, and gets “backed up”, raising the water level in the stream behind the ice dam blockage and can leak out over the side causing a major leak as well.
3). When running the pump in extreme cold weather, we are circulating the water and exposing it to the cold air. This can cause the water to get colder, which puts more stress on the fish. What we need to understand is that when a pond is not running, there is a natural stratification of water temperature that occurs. The ground under the pond is warmer, thus it helps to keep the water a bit warmer on the bottom than on the top where it is exposed to the cold air. This is why ice forms on the top and your fish stay on the bottom. By circulating the water, mixing it up and running it over the waterfall, more water is exposed to the freezing cold air making it colder than it normally would be. That being said, running air stones in the winter is very important to keep the pond aerated, but we don’t want the air stones to be placed on the bottom of the pond during the winter as they are in the summer. This is for the same reason of not circulating the water as much. In the winter, your air stones should be placed higher up in the pond, perhaps on a shelf. By circulating the water during the winter we are cooling the water even more causing the fish to be under more stress and the ice may form sooner and freeze thicker.
4). My final point is that you and your fish can rest easy. Everything is taken care of. The filters are drained and cleaned, pumps and UV lights are safely stored away and all pipes are blown out so they don’t freeze and crack. Your fish can also relax, and survive in a safe environment. There is no risk of finding your pond water all drained out. Working to fix things in freezing cold weather when the pond is covered with snow is not easy. Your water hoses may all be buried in snow and ice, frozen solid and your water supply should be turned off as well making things very difficult. Let’s also remember that most people don’t spend as much time outside observing their ponds in winter as we do the rest of the year, so when we do go out to see it, we may find a big problem that has been building for a long time. Thus making it a more serious problem. That’s why you don’t run your pond all winter!
What to expect come spring…
Shutting the pumps and filters off all winter also means that there is no filtration. However, we are not feeding the fish all winter, and the amount of waste being generated is very little. As the water temperature drops, so does the metabolism of your fish. I have not had any issues shutting down the filters over the winter. As the weather warms up in spring, we can start up everything again, and we may find the pond water to be green (sometimes it’s not). This will clear quickly if you have a UV light. Also, we may see some foam building up on the surface of the pond. This is due to the organics that may have built up in the pond over the winter. The foam or bubbles form due to a process similar to protein skimming, where the organic molecules stick to the oxygen molecules and float to the surface. For this reason you will see this more around your waterfalls or the “boil” on the surface from your air stones. This can be reduced by doing a couple partial water changes to dilute the concentration of organic molecules in the water column. Water changes in the spring are always a good idea to do anyway. If you typically add salt to the pond in the spring, that can cause some bubbles as well.
Final Thoughts
I hope this article helps you to understand the pro’s and con’s of running a pond all winter. This advice will vary according to where you live, and how cold your winters typically get. If it is possible to run your pond all winter without the risk of all these problems then do keep them running, and just adjust what you need to accordingly. But if you live in an area where extreme cold for long periods of time occur frequently, then you may want to consider shutting the pond down before it gets too cold. For more information on caring for your pond in the winter, watch my YouTube video on “Winter Care”. https://www.youtube.com/watch?v=o6EpDkTQlZI Thank You!
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