Koi

Nowadays, there is an overwhelming selection of media available for use within your filter, but they all fall into one of three categories.

Mechanical media will physically remove waste and particles from the water. In modern Koi ponds, mechanical media has changed from brushes that were used in the first stages of the filter system for collecting large waste particles, to the use of finer filter flosses in the later stages for collecting fine particles and polishing the water. The exception to this is on a pump-fed pond where dedicated settlement filtration (like a sieve or vortex) may not be used, and brushes would still be the main mechanical filtration.   

Biological media is used to house the maximum amount of beneficial bacteria to process the waste products from the fish. Biological media can come in many guises, from the traditional rock media like spa or laytag (which are now considered out of date by many), to the new lightweight, easy-to-clean, plastic media (which have a massive surface area in comparison to the volume required).

Then you have media like Japanese matting, which has lasted the test of time and is still considered by many to be one of the best biological medias. Of course, the choice of media may not be one that you make, because many of the filter systems that are proving popular have their own media, and can only run with this!

Chemical media are generally only used if a specific problem arises, for example, if a high ammonia reading occurs, zeolite may be used. Zeolite is a rock media that has the natural ability to absorb small amounts of ammonia, for a limited period of time. Other media that could fall into this category include PIP titanium balls, which cause a chemical reaction to occur as water flows over them and they are exposed to a light source. PIP titanium balls could be considered one of the most expensive medias with a small bag costing over £135!

As for the cost of filter media, it is fair to say that the price of media varies so greatly that it is hard to give you a guide. But if you purchase a filter system, nine times out of 10 you will find that it comes with media included within the price.
 

Written by Keith Holmes