A common misconception many people have regarding winterizing your pond is that running water will somehow hurt your fish. It’s important to keep in mind that fish are cold-blooded creatures and that they will adapt to whatever the water temperature is. In addition, running water freezes more slowly than still water, so you can run your waterfall well into winter as long as you take some precautions to make sure that your waterfall or filter outlet flow does not freeze and divert water out of the pond.
To help your fish survive during the winter, start introducing a vitamin and mineral supplement to their diet during the fall. This will help them to build up their immune systems and add the needed fat in order for them to make it through their hibernation cycles.
If the water temperature drops below 50 degrees, do not feed your fish. They go into a kind of hibernation and their bodies cannot absorb food at this time.
Many people think that a pond de-icer (heater) will help to protect their fish during the winter. A de-icer can help with the buildup of carbon dioxide under the surface of the ice that forms on the water.
A better option for winterizing your pond for your fish is to use an aerator/circulator decontaminator unit. By using it all year round, you will greatly enhance the overall biological process by keeping algae at bay, plus you will continuously supply dissolved oxygen to the pond during the winter via the air bubbles that the decontaminator unit provides.
If you are using the EcoBio-Block line of products to help prevent ammonia build-up and to increase the presence of good bacteria that will keep the water clean and healthy for your fish, rest assured that the bacteria in the block will simply hibernate along with your fish until warmer weather when it will start producing again just when your pond is starting to need it.
Tropical plants will not make it through the winter if they are left in your pond. When the water temperature falls under 60 degrees Fahrenheit, they should be removed. Depending on the species of plant, you could keep them in your house as house plants or consider them as annuals and purchase new ones to fill your pond the following spring.
If you have an out-of-the pond biological filter, you can let it continue to run until there is a chance that the outlet water flow can freeze and divert water from the pond. If/when you shut it down, let the water drain via the siphon effect or via the drain plug. Only clean the leaves and dead plant matter from it. If you have an in-the pond biological filter, remove it before winter begins. If you have a non-oil filled pump, you can leave it on during the winter so long as it is well under where the ice will form.
During the winter, you should check to make sure that everything is going well. If your pond has completely frozen over, NEVER break the ice by pounding on it. Keep in mind that the decontaminator unit is still providing oxygen and removing toxicants for your fish under the ice. To reopen the hole in the ice, either use a de-icer or pour hot water over a section of the ice until the hole reopens.
Preparing ahead of time to winterize your pond for your fish and plants can ensure that they will survive the winter and that the pond will be in optimal condition for them when they come out again in the spring.