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Can You Use Diatomaceous Earth Filters for Fish Ponds?

David Roberts

Most Koi fish ponds on display in stores have crystal clear water. If you purchase one of these Koi ponds and try to achieve the same results in your yard, realize that it is not that easy to maintain clear water for Koi viewing pleasure. Your Koi pond will need a combination aeration and filter system to screen the algae and particles out that cloud the water. Diatomaceous earth, or DE, is made from tiny organisms called diatoms that die and leave fossilized remains in the soil.

How They Work

You have to be able to see the fish in your pond if you want to enjoy them.

When the diatoms die, the soil around them are filled with microscopic sized cavities that can be used in filtering the water in ponds, pools and in large scale industrial applications. DE filters trap particles that are too small to be trapped by other filters and keep them out of the water without filtering out the good bacteria needed in the pond to keep the fish healthy.

DE Powder Added Alone

Some pond owners have used a scatter method to sprinkle DE in the pond directly. While the particles that need filtering out will bond with the DE and sink to the bottom of the pond, no one can reach every square inch of the pond by casting DE in directly. The particles that are not bonded as the DE sinks to the bottom of the pond remain suspended in the water. There is no feasible way to retrieve this DE that is now at the bottom of the pond as just another type of mud.

DE Powder in Filters

Some pond filters are filled with DE straight from the bag. The DE is an off-white colored course powder packed into a container. The water is drawn into the container where it spills over and through the DE material and falls into the water cleaned and ready to use. The disadvantage to these types of filter containers is that the DE has to be replaced often with clean DE and cannot be reused easily. Used DE can however be recycled as an additive to gardens and flower beds to kill slugs and other pests without harming the plants.

DE Filter Liner

With the filter liner types of DE filters, there is a coffee filter-sized material that is sewn around a packed amount of DE inside. These types of filters are used in specially designed containers that allow for the easy removal and cleaning of the filters for reuse. The one drawback of using these types of filtering mechanisms is that the motor tends to burn out with more than three hours of use at a time. To choose the right one for you, you will have to know the amount of water needing cleaned and get one with a motor that will do the most work for your pond in the three hour time limit you have.