pond filter media
Bio balls!

There are various different pond filters that help to keep the water in fish ponds clear and healthy. While they work differently, either mechanically or biologically, what they all have in common is their ability to get rid of debris and muck that pollutes the water. And to be able to do this, most filters utilize some sort of pond filter media.

The Way Pond Filters Work

Mechanical and biological filters work completely differently to one another and the media they use is specific to the filter type. So when you get your fish pond supplies, you must be sure to buy the right media for the filter you are using.

The main difference between a mechanical and a biological pond filter is that:

  • a mechanical filter will sieve out or strain the dirt and algae
  • a biological filter will break down this same dirt and algae and basically neutralize it

Mechanical Filters

The simplest mechanical filter has a type of open-cell foam (which is the filter media) set over the pump strainer. When the pump is operating, all the waste is literally pulled into the foam.

A more complicated and more effective mechanical filter is made by layering different types of filter media in a casing of some type. Usually there will be open-cell foam at the base of the casing, with fine gravel or some other type of filter granule on top. Mechanical filtration will occur in the top gravel layer and, if the pump runs continuously, a certain degree of biological filtration will take place throughout all the filtration media as well.

Biological Filters

The way biological filtration works is that the waste products are turned into harmless materials by the action of the bacteria that flourishes on the filter media. But to be effective, the filter, and therefore the pump, needs to run continuously. If the pump is switched off, the bacteria will die in just a few hours, and it will take several weeks for it to become effective again.

Biological filters can work with either submersible or surface pumps, and either way, the water is pushed or drawn through the inlet pipe into the filter at the top, and then aerated through jets or holes that pass through one or more layers of suitable media.

Several types of media may be used, depending on the design of the filter: for example rough gravel, open-cell foam, resin-bonded fiber matting, coarse sand, and other specially manufactured granules. The water passes through whatever media is in the filter, and the clean, purified water returns to the pond through the outlet pipe at the base of the filter unit.

More advanced biological filters consist of several chambers with valves, but they still use the usual filtration media.

The size of filter you choose will depend on the volume of water in your pond and the number of fish you keep in it. If it doesn’t have the required capacity it simply won’t keep the pond water clean. Also remember that every type of filter needs to be cleaned regularly, and the filter media needs to be replaced whenever it is necessary.

1 COMMENT

  1. […] Filters suitable for ponds come in all shapes and sizes and there are several types including biological filters, mechanical filters, and chemical filters. While they look quite different and operate in different ways, all filters have the function of either sieving out waste and dirt, or filtering it through various types of pond filter media. […]

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