Many pond owners wish to keep fish in their ponds all year around. This is easy to do, even in cold climates, with the use of pond heaters or deicers. The purpose of a pond heater is not to keep the entire pond a certain temperature, but rather to keep a hole melted in the surface of the ice. This hole allows gasses from decomposing fish waste, leaves, twigs and other organic matter to escape. If left trapped in the pond, these gases create a toxic environment and can poison the fish.
There are actual heaters that will heat up the water but can be costly in electric costs and the actual product will be much more expensive then the pond deicer which is also known as a pond heater.
In some cases, pond heating is used to keep large areas of water within a specific temperature range when a controlled temperature environment is required. For most fish this is not necessary, and all that is needed is a small hole in the ice. When the water drops below a certain temperature, most fish will swim to the bottom of the pond and go into hibernation. Once their activity diminishes they no longer require food. In fact, fish food added to the water in winter will probably not be eaten; instead it will decompose and contribute to toxic gas build up in the water.
The two types of pond heaters are submerged and floating. Floating heaters rest on the surface of the pond and keep a small area from freezing over. Floating heaters are the more efficient of the two and usually are all that is needed. Submerged heaters are capable of keeping a smaller amount of water, usually less than 300 gallons no more then 18 inches deep from being ice covered
Electric pond deicers require anywhere from 100 watts to 1500 watts to operate. The wattage necessary to keep a hole in the ice depends largely on the climate but also on other factors such as how much sun and shade the pond receives. Wind would also be a factor.
Another way of keeping an opening in the ice besides a heater during the winter would be by using a pond air pump or pond aerator that will also add oxygen to your pond. More cost up front, need to protect from the elements, low in watts yet still a good choice.
