Understanding the Nitrogen Cycle Basics

Understanding the nitrogen cycle for your pond and quarantine tank is very important for the overall health of our koi and pond system. All decaying organisms on the planet go through a nitrogen cycle.

The nitrogen cycle basically cleans out your pond water through a biological process. All surface areas in your pond are also a source of the bio activity or nitrogen cycle.
Your pond starts with bacterium that begins to break down decaying matter, such as leaves, plants, koi food not eaten or any decaying waste in your system. This creates ammonia. Koi add the majority of the ammonia (80% through gills) feces,urine and slime coat.
This overload of ammonia to be dealt with in your system (pond,filter) is accomplished through a biological filter of some type. There are several types of filters on the market or you can build our own.

So how does the nitrogen cycle work? In its simplest form.

Once ammonia is present in your pond, other genes of bacterium start to reproduce, (Nitrosomonas). Nitrosomonas starts to oxidize (consume) and convert ammonia to a byproduct called nitrites. This can take from 2 to 4 weeks or more to accomplish a zero reading or none detectable ammonia reading. This means that the numbers of Nitrosomonas bacteria are at a level that can digest almost all of the ammonia. This will show up as zero (0) reading on your ammonia water test kit.
The first part of the cycle is completed.

Once nitrites are present in your pond another genes of bacterium start to multiply. These Nitrobacters start to oxidize (consume) and convert nitrite to a byproduct called nitrate. This can take twice as long to accomplish as they reproduce at a slower rate. It can take four to eight weeks for the nitrobacter family of bacteria to reproduce in sufficient numbers to balance the nitrite level to zero (0). This will show up as a zero (0) on your nitrite test kit.
Second Step of the cycle is completed.

Nitrates are the last phase of the cycle or final product of the ammonia breakdown. Nitrates are considered harmless for the most part. However large numbers are bad for koi. Numbers vary from paper to paper but 100 ppm or lower is generally accepted to keep the ppm numbers (as a maximum). Many ponders have between 5 to 20 ppm. Nitrates can be removed with small water changes. Plants use nitrates as well.
Third Step of the cycle is completed.

Your filter is cycling and all is well. NOT QUITE YET. Please read.
As your pond starts up, New Pond Syndrome. Your koi are exposed to health issues and possibly death. It is estimated that 60% plus of kills in ponds are caused by this. Many ponders well quit after this happens to them. Why? The ammonia that is created well be at high levels until the nitrosomonas bacteria has populated to create the balance of zero ammonia. This spike (high ammonia) damages the gills and can kill the koi. The same occurs with the nitrite cycle, nitrobacter. This spike(high nitrites)can damages the organs of the koi and also develop brown blood disease.

Now that you know the basic concept of the nitrogen cycle. I believe you well have a different outlook on your whole system. So remember your filter and water parameters for the most part is dictated on how you feed it.