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Hozelock Ecocel conventional biological pond filters for fish ponds

Pond Filter Clean Water To Allow Fish To Survive in Their Own Pollution

The simplest of all pond filters is the “black box” type. The Hozelock Ecocel handles ponds up to 9,000 litres in volume. Any pond filter of this type can be enhanced (ie increase pond capacity) by increasing amount and/or type of pond biomedium.

Building a pond filter of such a type requires a rectangular or other shaped plastic box which contains some or all of the following. It is easy to make home made pond filters once you have an appreciation of the following:

Open cell foam used to mainly remove leaves, and larger particles of whatever can get into the pond filter. It has a limited amount of biological capacity

Brushes as an alternative or adjunct to foam to remove solids

Plastic tubes, plastic balls or other plastic shapes or other biomedia on which bacteria accumulate

Inlet pipe, outlet pipe and overflow pipes back into the pond perhaps. If you want to see how easy a diy pond filter is go to your nearest stockist and take a look inside one of the pond filters you see there.

WARNING bio filters do not clear green or murky ponds as many people claim. To ensure a clear pond an UVC is needed ... this kills suspended algae which can then be removed by the bio filter. While still living algae are very very very tiny and just pass straight the pond filter. In other words for a crystal clear garden fish pond you need BOTH a bio filter and an UVC or ultra violet clarifier

The simplest homemade pond filters contain almost anything you can imagine from hair curlers to gravel.

BUT ... if it was me and because I'm a bit ham-fisted I would buy a box filter like this one above and shown in table below ...