There are three types of water filtration: mechanical, chemical and biological.Using one type or all three depends on the size and type of the aquatic ecosystem in question. Big ponds and lakes rely on biological filtration to keep the water clean while water gardens and small ponds are usually designed to involve all three types.
Mechanical filtration, like pumping water through filter pads, physically removes debris from the water. Chemical filtration involves chemically attracting particles to clean a pond, like using activated charcoal to remove tannins, the copper coloring, from the water. With biological filtration, living organisms like pond plants and beneficial bacteria clean the water.
A pond owner’s filtration needs are integrally tied to the type of pond he keeps. There’s a big difference between a simple water garden with a few small goldfish and a formal garden designed specifically for koi. A single large koi creates more waste than slews of small goldfish. Indoor ponds have different filtration needs than outdoor ponds.
The most important types of filtration for water gardens and goldfish ponds or koi ponds are mechanical and biological filtration. Most water gardens and backyard ponds have a pump to move the water. That pump will also pick up suspended particles and move them throughout the system. Adding an area for suspended particles to be trapped, such as a skimmer or waterfall box with filter material helps keep these particles from clouding up a system.
Adding materials that provide ample surface area for bacteria to grow also provides filtration benefits. Consider a bog filter, for example. By creating a bog filter, an area with a gravel surface dotted with plants, pond water stays cleaner. The gravel surface provides an anaerobic area, while plants open up spaces in the gravel, adding oxygen, which promotes decomposition and nitrifying bacteria in pond ecosystems.
A filter doesn’t have to be an ugly canister sitting next to a pond. A water filtration system can also be a beautiful stream full of bright flowering plants.
Michelle Hess is a senior service specialist and director of National Pond Service. She has three degrees, in Natural Resource Conservation, Environmental Studies and Fisheries Technology, and has consulted and worked with customers of National Pond Service since 2009.National Pond Service is a full-service pond, lake and water feature management company specializing in nonchemical remediation and water management services. With a focus on caring for aquatic environments, National Pond Service offers effective, environmentally friendly pond and lake maintenance, remediation and consultation services.