Koi Pond Filters

Every koi pond needs to be properly filtered.  This is because the koi produce fish waste and urine.  Fish waste contains toxic chemicals and likewise the urine contains ammonia and other nitrogen compounds.  These are all poisonous to your koi and therefore need to be removed from the pond.

There are two essential types of koi filters needed to remove solid waste and nitrogen compounds.  The first is the mechanical filter that cleans solid particles from the water.  It usually employs a vortex to slowly spin the water.  Gravity and the spinning water drag the solid waste out of the Koi pond.  These particles become trapped in the filter and then can be cleaned out during the regular maintenance of the pond.  The biological filter relies on bacteria to break down poisonous nitrogen compounds (like ammonia) into less harmful substances like nitrates.  Nitrates are only harmful to Koi in large amounts.  To understand the importance and role of these filters, you need to know about the Nitrogen Cycle.

Koi pond mechanical and biological filter

There are two other types of filters that are useful.

The third type of filter is the chemical filter.  This type of filter is to eradicate poisonous chemicals from your pond water, such as pesticides, insecticides, chlorine, etc.  It normally uses activated carbon to remove these chemicals.

The last type of filter is the UV filter.  The function of this filter is to remove fungi, dangerous pathogen and algae cells using ultra-violet radiation.  However, in a koi pond, the algae and fungi are generally kept under control by the Koi themselves that eat them.

Koi pond filters use a pump to force the water through it.  With a big area like a pond, the strength of the filter is not able to circulate the water on its own.  The pump pushes the water and circulates it through the pond.

In addition to the pump and the pond filter, you may want to consider adding a small fountain, a waterfall or some other water device.  This is important for aeration of the koi pond.  Koi need a minimum of 3-5 mg of oxygen per liter of water otherwise they suffocate.  But the warmer the water gets, the less the amount of dissolved oxygen in it.  Thus, it is important to control the water temperature of your koi pond.  For example, during winter use either a heater or just cover your pond and during summer, have a fountain or waterfall to churn the water so that more oxygen from the air is dissolved into it.

It is important to test the chemical make up of the water of the pond weekly.  You can do this one of two ways.  You can either bring a sample of the pond water to a local pet store to have them test it for you or you can purchase a home testing kit and test the water yourself.  It is important to keep the chemical mixture in the water at a normal and healthy range for your Koi fish.

Doing all these will ensure your Koi live in a clean and healthy koi pond, giving you the pleasure of enjoying your Koi fish for many decades to come.