The following information is intended as a basic guide to some of the principles of pond filtration, please feel free to email or call for more information.

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The reason for having a filtration system on a koi pond is to create a clean, pollutant free environment for its inhabitants to live. The fact that your water may be crystal clear does not mean that the water quality is suitable for your Koi - CYANIDE is toxic for example.

There are three methods of filtration, mechanical, chemical and biological.

Mechanical Filtration
Mechanical filtration removes the solids waste prior to the water entering the chemical or biological stages. This is important as the solids can cause blockages further along the filtration system, heavy build up of solids waste can lead to poor water quality, which in turn will cause koi health problems, disease and death.

To a lesser or greater degree, all filter media use mechanical filtration, the more delicate the filter medium, the better the mechanical filtering.

The more delicate the media is, the higher the risk of blockage. Many ponds use a settlement chamber, such as a vortex as the first stage of the filtration process. A vortex is a round tub in which the water is whirled. This effect sucks the heavy waste parts to the bottom of the chamber where it can be flushed away. This can save time spent cleaning the filter as less solid waste is entering the latter stages of the filter.

In recent years the use of products such as the 'Answer' have become more popular. The 'Answer' is a self cleaning sieve which can filter waste particles as small as 20 micrometers, Added to a vortex this can mean far better water quality without spending hours cleaning filters!

Chemical Filtration
This method involves absorbing chemicals such as ammonia and other toxic pollutants. The most popular chemical filtration medium in aquaria is active carbon. The disadvantage of this method in a pond are the expense and the absorbing capacity cannot be renewed. Zeolite is more popular in pond filtration systems as it can be recharged by soaking in a heavy saline solution prior to being rinsed and reused. Do not use salt in a system with zeolite as the toxins stored in the zeolite will be released into the pond. Also remove any chemical filtration medium prior to treatment being added to the pond as these also may be soaked up.

Bioloical Filtration
Nitrosomas and Nitrobacter are bacteria which convert harmful ammonia into nitrite and finally relatively harmless nitrate. Both of these bacteria are aerobic and will only thrive with a good oxygen supply.

Nitrificating bacteria attach to and grow on filter media. The more surface area the filter material has the higher population of bacteria can grow on it. There is a wide choice of filter media available, modern day highly porous filter media such as Kaldnes means that modern day filter units can be much smaller than would have been acceptable until quite recently.

Nitrificating bacteria reproduce slowly, it can take between 1 and 2 months for a biological filter to start to produce enough bacteria to sustain a pond system. To avoid dangerously high levels of toxic waste levels in a pond, do not add to many fish at one time and do not switch the filter system off for an extended length of time. Nitrificating bacteria will die after only a few hours without oxygen, leaving behind anaerobic bacteria. Anaerobic bacteria is toxic to fish and is a common cause of disease in fish. A dirty pond/filtration system can harbor anaerobic bacteria and koi diseases such as outbreaks of parasite infestation and bacterial problems may occur.