Overwintering your pond is a little trickier. It largely depends on the weather conditions in your area and the pond's depth.
The pond can be drained and covered, and all life within it can overwinter elsewhere or the pond can be altered so as to overwinter the way it is. If your pond is deep enough, move frost-sensitive plants below the frost line. Remove fish or take precautions for their survival. Stop feeding them when the water temperature drops below 50 F. The fish are less active now and do not require food. This food will only pollute the water. Remove as much plant debris as you can. In moderate climates consider using an aerating nozzle or bubbler to keep the water moving so that the surface does not freeze over completely. Depending on where you live, you may have to use an electric pond heater in addition to an aerating nozzle. This is important because you have to have an open area to allow for gas exchange to take place, and the fish still require oxygen to breathe.
If your pond is frozen over for more than a few days your fish may suffocate. It is important that you have an open area that allows toxic gases from within the pond to escape and for oxygen to get into the water in the pond. In moderate climates, where ice is rare, you can use a pot full of hot water set on the ice surface to melt it open again. If you need your pot back before Spring, attach a rope or string to the handle so you can retrieve it when it melts through the ice and falls into the pond. Do not pound the frozen pond surface with a hammer as this could kill the fish. In colder climates, you will need to have a floating pond de-icer operating continually.
Unless you can use them year-round, don't forget to bring your pumps, pond filters and fountain equipment in for the winter. Consult the manufacturer's operating instructions for proper winter storage procedures for your pumps and filters. In our opinion, the best method for storing your pump over the winter months is to remove it from the pond, clean it thoroughly and run clean water through it for several minutes. Then, keep it in a bucket of distilled or purified water above freezing temperatures. A heated garage or basement would work well. Once every few weeks, turn on the pump and let it run for a minute. Remember to drain any water lines that my crack when filled with ice.
The unpredictable nature of Winter in Canada and the Northern United States makes overwintering your pond more of a challenge. We recommend that valuable and sentimental life be brought indoors if there is any doubt about safe and successful overwintering in the pond.