Koi Pond – Filter media

There is a wide range of filter medias to choose from for your filter system. The following are just some that are available in the market:


Eficient at removing debris and blanket weed, brushes were very popular until a few years ago.

However they require regular cleaning and also a lot of maintenance, and is time consuming. They can  also prove to be very difficult to clean around the steel spine.


Flocor comes in two sizes, is lightweight and very effective. It is widely used of all the filtration media because it is easy to install, clean and maintain. The media has very good biological surface area per square inch than many other types of media.

They are usually placed in bags to facilitate easier removal and cleaning.


Alfagrog is a volcanic rock and is still a favourite with many koi keepers.

This is also quite heavy and very rough to the hands so many koi keepers put it into net bags which are obtainable from most koi dealers.

Japanese matting

Japanese matting can be used for the full system, or in one or two bays with any other media. It requires heavy aeration, but the up side is that it needs very little cleaning.

Japanese Oyster Shells

Oyster Shells are used to maintain a balanced PH level in the ponds water. They are used to raise the PH level in water and are only recommended to be used in cases of lower PH levels.

They should be located in the last bay of the filtration cycle, and you will need to monitor the PH levels within the system

Crystal Bio Media

Crystal Bio Media is a eco-friendly glass media which is produce by heat of up to temperatures of 900 °C. This process creates a media with a surface-area up to ten times greater than most plastic alternatives. The media increases biological filtration, does not require much maintenance, and enhances nitrification. The Crystal Bio media can be used as a stand alone biological filter or as an addition to an existing filter system.

Kaldnes K1

Kaldnes media provides the maximum active surface area for the bacteria to colonise, more than other types of static media. It is this process which removes harmful ammonia and nitrite from the water.

The Kaldnes media works by moving within the filter and displaces old dead bacteria on the outside, making space for new younger heavier feeding bacteria to rapidly colonise. Within the wheel is a protected surface which enables colonies of bacteria to naturally follow their lifecycle, of maturing, dying and then fueling the latter stages of the nitrification cycle.

It is designed to provide habitat for both young and mature beneficial bacterial colonies. This process removes harmful ammonia and nitrite from the water.

Filter foam

Normally used in three layers and in smaller filter systems, therefore it is not suitable for the large filter units as they would require cleaning almost every day, and eventually they have to be replaced.


Bacta-Pur® LITHAQUA is a marine mineral with a high content of minerals, trace elements and carbonates.  It adjusts the mineral balance and improves the water quality and can be uses as a pond substrate for bacteria to grow on and for fish to play in, or use it as a filter medium.

It also neutralises acid pH and helps to restore carbonate alkalinity.

Bacteria House Media

The Bacteria house is a ceramic media that has been heat treated at 1300°c for 60hrs.

It is a porous media, allowing mechanical filtration where large organic solids and decaying matter are degraded at a far greater speed than conventional media.