Instructions
Determine the size of your pond, approximate number of fish and plants, and any water flow areas such as waterfalls or outflow pipes. This will help you decide the type and size of heater or de-icer to use.
Decide if you need both a de-icer and a heater or just one of the two. A de-icer is usually used in ponds no bigger than 35 feet by 35 feet, and they need a source of electricity to operate. A de-icer is usually not required if you are using a submersible pond heater, though they accomplish different tasks. If the surface of the pond ices over even with a submersible heater, a de-icer should be used as well. The de-icers only heat the immediate area at the surface of the pond around where they are located.
Consider whether or not you need a submersible pond heater. This is determined by how cold the area you live in gets over the winter and the depth of the pond as well as consideration of the organisms living there and their cold hardiness. There are electric heaters that carry a higher risk of electric shock for both the pond and the person handling it, and gas or oil heaters that have a higher setup fee but fewer overall maintenance costs.
Research the average high and low temperatures in your area, and determine the coldest temperature as well. You will need to know this to obtain the best heater for the area in which you live.
Contact a store that sells pond equipment and discuss the options available. They can help you determine what will be best for your specific pond and offer installation advice or even install the equipment for you if they are local.
How to Warm Small Pools
There are two important items to consider when keeping a small pond heated during the winter. One is a submersible heater that keeps the water above a certain temperature, and the other is a de-icer that floats on the surface. The de-icer keeps part of the surface free of ice so that toxic gases can escape and oxygen that organisms require for breathing can enter. If you are keeping living organisms in your pond all year round, you may need to consider using either one or both of these to keep them alive and healthy.