Keeping Your Fish Alive in Your Winter Pond
Pond heaters are really not essential to garden ponds, unless you have Koi or any other type of living creature in your pond year round. If you have Koi or other fish in your pond, it's extremely important that the pond water is kept at a stable temperature to ensure proper health for pond fish.
Pond heaters lie on the bottom of the pond and must be completely submerged when in use. Pond heaters are built with a rubber bumper surrounding them in order to prevent them from touching the sides or bottom of the pond. The controller for the pond heater must never get wet and should be protected from water at all costs.
Fish are usually ok in the pond during the winter, if your pond is deep enough. If you have a shallow pond you should use either a pond heater or a pond de-icer and possibly bring your fish inside, if you have the room. If you see bubbles forming under the ice, it could be methane which can be toxic to the fish if it is not allowed to escape. Wildlife aside, concrete ponds can form pressure cracks in their sides when frozen for awhile. Small ponds can remedy this by placing a pot of hot water on the ice surface until it melts through, allowing the methane to seep out.
Pond de-icers are sometimes mistaken for pond heaters, but are just as important if your pond contains fish and other living creatures. Submersible pond de-icers are not heaters; but they keep a small opening thawed on your pond's surface in order to allow toxic gases to escape and to allow oxygen to enter simultaneously. Floating pond de-icers can virtually keep the entire surface of a pond thawed because they float on its surface, depending on the volume of your pond. Pond de-icers contain automatic thermo-regulators that turn on whenever the water temperature drops below 40-degrees Fahrenheit.
To determine the size of pond heater you need, consider that it takes approximately 1000 watts of heater to heat 250 gallons of water to 10-degrees Fahrenheit - get out your calculators!
Prices for pond heaters are usually related to the heater's capacity. Prices for pond heaters usually range from about $440 to $800 online