Important Pond Gear for Fish Safety
A pond de-icer, also known as a pond deicer, is designed to heat an area of a small pond and keep the water in its area above 40 degrees Fahrenheit to prevent ice from forming. It should not be confused with a pond heater.
The main reason why you don't want ice over your entire pond is because your pond needs to release toxic gases from decomposing organic matter, usually methane. The de-icer can allow your pond to get the oxygen that it needs. This is especially important if you have fish.
Pond de-icers are meant for small backyard ponds no larger than 35' x 35'. The manufacturer of the unit sets the default temperature, which is usually around 42 degrees Fahrenheit.
De-icers can be floating, submersible or convertible. They can be plugged into your pond's power control center. An aerator is also a good, if not better, comparison to the de-icers because they give the pond the oxygen it needs while maintaining an area of the pond to stay ice-free to allow the toxic gases to escape.
Floating De-icers: are a good purchase because they move around the pond and open up a large area of ice to allow the chemical build-up to disperse in the air. However, it operates on electricity, so those far reaching ponds will be unable to take advantage of this fish saving device.
Submersible De-icers: are controlled using a thermostat, so they save money in the long run, especially in the winter when there are warm spells. These are better options for shallower ponds. The submersible de-icer sits on the bottom of the pond on a plinth and warms from the bottom up. Obviously, if the pond is too deep the submerged de-icer will not be effective in releasing gases, but it will help larger fish hibernate.
Pond de-icers are not essential if you have an actual pond heater. But keep in mind that a de-icer is NOT the same as a pond heater. De-icers usually range in price from $50-$70.
You may also want to consider plugging your de-icer into a Thermo Cube to keep it controlled to work at the necessary temperatures.