Winterizing Your Large Pond

Winterizing Ponds and Fountains

It’s finally time we put the summer months behind us and start hunkering down for a long, cold winter. For some, that means dusting off their skis. For others, it means gathering enough wood to keep the fires burning all season long. And for others still, it means winterizing their ponds to ensure their plants and fish survive the frigid temps.

But for most pond and fountain owners, it isn’t as straightforward as, say, winterizing your sprinkler system. But don’t worry — we’ve got you covered.

Here, we’ll tell you exactly how to winterize a pond.

Why is winterizing ponds so important?

If you live in a cold area, especially in places like Wisconsin and Michigan, it’s time to get ready. Winterizing pond filters and pumps is part of that preparation.

Make sure you remember to remove your surface aeration, as freezing water can do damage to pumps and everything else with your pond fountain or surface aerator. Even pond floats and nozzles can be damaged. Wintertime is a great time of the year to do maintenance on your system. If you own a Kasco unit, don’t forget to replace the anode!

But on top of that, if your pond is freezing over, remember the ice and snow will block the sun, preventing photosynthesis. Because of this, plants will stop producing oxygen and will die off, and your pond will start decomposing them, using even more oxygen.

How to Winterize a Pond with Fish

Thus, a potential case of very low oxygen can be dangerous for your fish. The good news is that, according to Kasco Marine, studies have found that you only need to have an open area of 1-2% of your pond’s total surface area to prevent a fish kill.

There are two main ways to deal with really cold ponds: de-icers and bottom, diffused aeration systems.


De-icers sit near the top of the pond and move the warmer water at the bottom up to the surface. This temperature change melts the ice away and keeps it from re-forming. The open space allows oxygen into your pond and a vent for harmful gases to be released. This process is called gas exchange.

Bottom Aeration

In case you don’t already know, bottom aeration using a diffuser system pumps air from a compressor through tubing to a diffuser or series of diffusers at the bottom of the pond. As the bubbles rise, they move the warmer water to the surface, thus also melting the ice.

A note of caution, though, according to Kasco Marine:

“When using a diffused aeration system in the winter, you may need to reduce the number of diffusers used to avoid “super-cooling” which can be dangerous to fish and possibly make the ice even thicker.

Another tip is to move the diffuser heads closer to the shoreline in the winter. This will help prevent supercooling since it isn’t drawing water from the deepest part of the pond or lake and it will maintain an open water area that touches the shoreline.”

We at Fountain Mountain stand firmly by Kasco’s recommendations and products. We don’t think you will find a more resilient and energy-efficient product on the market.

When should you winterize your pond?

Some people like to get a jump on winterizing their water features. Others like to get as much use out of them before the days grow short and the temperatures drop. There’s no exact date or time set for winterizing ponds, but we recommend taking all the necessary precautions at least one week before the first freeze of the season.

Scott Fountains, the exception

We should mention before we close that Scott aerators and fountains do not need to be brought in during the winter if you keep them running all the time. Keeping them running will also provide an air hole through ice.

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