The Nitrogen Cycle

If you want to keep Koi, it is imperative for you to understand the Nitrogen Cycle.  This cycle affects the water quality in your Koi pond and means life and death to your Koi.  The purpose of understanding the Nitrogen Cycle is for you to eliminate ammonia and nitrites from your Koi pond water.  Here’s how the Nitrogen Cycle takes place.

When Koi urine and produce waste, this resultes in the production of ammonia.  Ammonia is also produced by decomposing uneaten food.  That’s why you should always remove all uneated food from your pond about 10 minutes after feeding.  What happens is the Koi waste and excess food will break down into either ionized ammonium (NH4) or un-ionized ammonia (NH3).  Ammonium is not harmful to Koi but ammonia is.  Whether the material turns into ammonium or ammonia depends on the ph level of the water.  If the ph is under 7, you will have ammonium.  If the ph is 7 or higher you will have ammonia.

When ammonia is present, bacteria called nitrosomonas will develop that will change ammonia into nitrites through oxydization.  So we no longer have ammonia in the tank, but we now have another toxin to deal with - nitrites.  Nitrites are just as toxic to tropical fish as ammonia.  This would take about 1 to 2 weeks of a new pond.  If you have a test kit, you should be able to see the nitrite levels rise around that time.

In the presence of nitrites, bacteria called nitrobacter will develop and they will convert the nitrites into nitrates.  Nitrates are only harmful to your Koi in large amounts.

The Nitrogen Cycle and your Koi

The quickest way to rid your aquarium of nitrates is to perform regular partial water changes.  Once your pond is established you will need to monitor your water for high nitrate levels and perform partial water changes as necessary.

To eliminate the ammonia and nitrite from your Koi pond, you need a Biological Filter.