Pond Filters

Types of Pond Filters

Intake Filters are usually small (perhaps 3x3x6 inches or so) blocks of open-celled foam that often come in the box with the pump. These are far too small to be effective at waste removal or reduction, and serve only to prevent pieces of debris from being sucked into the pump’s intake and stopping or damaging the pump itself. Advantages: inexpensive; easily removed and rinsed clean; output of pump can still be used to run fountain or waterfall. Disadvantages: small surface area means they plug with debris quickly; often need to be rinsed daily or even more frequently; do not improve water quality significantly. Things to Look For: very coarse foam for good flow; firm attachment to pump; multiple filtering surfaces so a single leaf cannot block flow.

Filters may be used in combination to take advantage of each filter’s strong points. A common setup is to attach a submersed filter on the intake side of the pump, filled with coarse media to prefilter and protect the pump, and also an external filter on the output side, filled with finer media to catch smaller particles and biomedia to improve water quality by reducing ammonia and nitrites. Such a complete system not only provides the best filtration, but also can result in longer times between cleanings.

Sizing the filters.

Regardless of the pond size, a small filter is better than none, a medium better than small, and large better then medium. The bigger a filter is, the more waste it can catch or process between cleanings, and the more fish can be safely maintained The trade-offs of course are that bigger filters cost more and take up more space. Another concern is to match the filter to the pump’s output. An undersized filter will either restrict the water flow, or worse, leak water from the system. In such cases, a bypass should be installed to divert water to another water feature, or better still to another filter