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.
You will find a full range of different filters alongside the pumps with all your other fish pond supplies. If filter media is required, this will be supplied with the filter. But eventually, the media will need to be removed and cleaned, and sometimes replaced. The manufacturer’s instructions on the packaging will tell you how often to clean and/or replace pond filter media.
Here is a description of some of the types of filter media you might need for a biological filter. Do make sure that you buy the correct sort for the filter you have purchased.
There are various types of filter matting, usually made from plastic derivatives. This material does not look unlike some of the scourer pads that we use for cleaning dishes and pots and pans. Generally, it is quite rigid and very durable, and suitable for use in biological filters, settling tanks and in pre-filters.
Matting sheets are available in different densities, each supplied in a different color. For example one very popular brand uses black for its super-coarse matting, dark green for coarse, blue for fine, and grey for super-fine. The sheets can be cut using a normal serrated kitchen knife.
This same matting is also available in a rolled form that is six inches wide and has a 22 inch diameter to fit most whiskey-barrel style filters.
Fiber Filter Material
Manufactured from recycled material, this type of pond filter media comes in different thicknesses (from one to two inches), in different colors and densities, that may be an open-weave or dense weave. It is more effective than the old-fashioned open cell foam.
Beads, Balls and Blocks
Various specially formulated beads and balls are available for a range of different filters.
For example, there are little beads that float because the manufacturer adds air to each individual bead. The more buoyant they are, the better, because the beads stay close together at the top of the filter during the backwashing process. The surface of these particular beads is dimpled so that there is more of a surface to them.
There are also various types of bio-balls. Some are made from a loose plastic medium that forms to any shape and is hard, so it doesn’t compact. This sort is buoyant and works best in trickle filter applications.
Then there is a sponge type that allows oxygen-rich water to be filtered inside each little ball. This, like some of the others, is a patented design.
Like beads and balls, little blocks of pond filter media may also be used to keep pond water clean and clear. Polyester blocks are a loose-fill media type that is not expensive and so is perfect for filling large filters.
Plastic Pond Filter Media
There are various types of plastic media ranging from rings to those that look more like hair rollers.
They are all light, open and won’t get clogged up. When you look at some types through the cross section, they look more like more like pasta tubes with internal wings or ribs. This additional surface allows for excellent bacterial adhesion and colonization of bacteria.
Another type of plastic media comes inside a black nylon mesh bag. The way these are made, they will fit into any shape of container or filter and will allow water to filter through in any direction. They are exceptionally easy to clean, because all you do it pop the bag under a running tap and rinse it off.
Hybrid Pond Filter Media
Although made of a kind of plastic, the newest hybrid technology has produced a filter medium that has embossed coils that provide an even larger surface area than other types. This is designed to resist clogging and to encourage bacterial growth.
A patented product, it has a “loose coil” effect that works best the dirtier it gets, which makes it ideal for filtering waste.
There is also a bag made with the same material (and hybrid technology) that can be used with other filter media including bio-balls, lava rock, and filter matting.
Other Pond Media Types
Other types of pond filter media include gravel, barley pellets, peat, zeolite (a special alumina-silicate rock), carbon pellets, and various types of rock, including lava.