If you have fish that you wish to winter over in your pond it's necessary to use a pond aerator. A pond aerator or small recirculating pump that agitates the water's surface will oxygenate the water. Why do you need to oxygenate your pond in winter? When people drown, their bodies are deprived of oxygen because their lungs fill with water rather than air. Fish obtain their oxygen from air that is dissolved in the water in which they swim. ... Oxygen diffuses into the fish through their gills, without aeration your fish will drown! (Well...technically speaking suffocate may be a better term.)
If you don't have fish in your pond a pond aerator can still be beneficial as it will help to continue to break down nutrients from leaves and debris in your pond and keep the water from becoming stagnant and foul smelling, but is not necessary.
Other options for winter aeration: a small recirculating pump may be used instead of an aerator. It will pump water up to the surface of the pond an agitate the surface (which adds oxygen to the water.)
Will a pond aerator alone keep my fish alive in winter?
No. An aerator adds oxygen to the water. If the temperatures drop you still need to be able to maintain a hole in the surface of the ice for gas exchange. What is gas exchange? Your pond slows down over the winter months, but it never completely shuts down. Leaves and debris continue to break down too, just at a slower pace than during warmer months. The process of the plants and debris breaking down creates methane gas. When the ice is allowed to completely cover the surface of the pond methane gas builds up and harms the aquatic life in your pond -including your fish. To prevent this use a simple deicer. The better ones are thermostatically controlled so that they consume electricity only when the temperatures drop. The deicer keeps just a small ring around the unit melted in the ice and allows the harmful gasses to escape. When installing a deicer for the winter be certain that it is placed a good distance from the aerator as the movement of water by the aerator may make it run more often than necessary.
If you have questions about how to properly winterize your pond please don't hesitate to call our pond shop (973)627-0515. We have the knowledge and supplies you need for proper pond winterization. Still feeling uncertain about how to winterize your pond? Just ask and we'll winterize your pond for you!
Jaak Harju has been designing, building and maintaining ponds and water features in Morris County, NJ, as well as across the Country
(even a few international gigs!) for almost 2 decades.
In 2010, his company, Atlantis Water Gardens in Denville, NJ, was awarded Certified Aquascape Contractor (CAC) Of The Year by Aquascape Inc. and in 2014 he received the distinction of Water Feature Artist of the Year and Master CAC.