Swimming Ammonia Factories

It seems odd that Mother Nature has seen fit to allow Koi to produce wastes that are toxic in the extreme, directly polluting their own environment.

But that's the way it is.

As Koi keepers we have to develop filter systems to cater for these wastes and bio filters that can take care of it as speedily as possible.

Koi eat a lot. Koi filter systems need to cater for this now and in the future.

The most important cycle of life that takes place in a Koi pond is called the nitrogen cycle. It is the most important because it is the one that has the potential to kill your Koi faster than anything else, save a bolt of lightning of a few zillion volts.

The nitrogen cycle is well understood and forms one of the cornerstones to good water quality. However it is only ONE of the cornerstones and there are a few others that have to be learned as well.

The cycle of Koi life is a logical one.

1. Koi eat food.
2. Koi use some of this food for growth.
3. Some of this food is used to produce energy for the Koi.
4. By products of energy production and any unused food is excreted as waste.
5. Waste takes two primary forms, solid organics and dissolved inorganic wastes.

The nitrogen cycle that takes care of the dissolved inorganic wastes. The solid organics represent significantly more of a challenge than is let on by many people and is the source of much debate and confusion amongst Koi keepers.

Traditionally these two wastes have been dealt with by mechanical filtration to deal with the solid organics followed by biological filtration to get rid of the dissolved inorganic wastes.

This will be dealt with in some detail further on under mechanical and biological filtration. For now however, it is sufficient to understand that Koi produce two distinct types of waste.

Koi are called swimming ammonia factories since this is the chief product of inorganic waste. Ammonia is chiefly excreted through the gills and urine of the Koi and this happens in a healthy Koi after feeding. It does not happen on a continuous basis but rather in one session after feeding and digestion has taken place. Small amounts of ammonia are continuously excreted as a result of energy production, but these are relatively small and can be ignored for now.

Remember now the importance of stocking densities. A 1 kg Koi will produce, for arguments sake, 1 mg of ammonia. In a lake, this will result in the ammonia concentration increasing by a completely insignificant margin, beyond any measurable means. Even 100 Koi producing 100 mg will have a zero effect. Consider also that in a lake Koi are unlikely to feed all at the same time. They are equally unlikely to eat a full meal in one session - they feed continuously and not in short bursts as they do in a Koi pond.

But 100 mg of ammonia in a Koi pond of 10 000l means that the concentration of ammonia immediately becomes measurable at 0.01 mg/l. This is significant. It becomes even more significant as your Koi get bigger - a 60cm Koi will produce 8 times as much ammonia as it's 30cm counterpart!

After feeding then, a Koi pond typically experiences an ammonia peak - a peak that is not ever experienced to anywhere near the same extent in a natural environment.

Ammonia is highly toxic to Koi and has to be removed as fast as possible from the Koi pond. This is done by using useful bacteria that break the ammonia down firstly into nitrites which are still highly poisonous to Koi, and then in turn using other bacteria to break these nitrites down into nitrates, which are relatively harmless and are a great source of plant food. Bear in mind that nitrate in concentrations of more than 100 mg/l however are dangerous to Koi.

That's the nitrogen cycle in a nutshell: Food for Koi to Ammonia to Nitrites to Nitrates to Plants to Food for Koi. Dead simple really. Dead Koi also if you get it wrong.

Ammonia is bad.

Ammonia is toxic to Koi. You should aim to be rid of it as fast as possible. Note that ANY biofilter will eventually break down all ammonia in a Koi pond. But a bio filter that can rid a Koi pond of all ammonia as fast as possible is infinitely preferable to one that takes twice as long to get the job done.

You can never have a bio filter that is too big for a Koi pond. Bear in mind that these swimming ammonia factories grow bigger and as they do the amount of ammonia that they excrete is directly proportional to their weight. You bio filter has to be able to cope with the situation in which your Koi are at or near their full adult size. It must also still do so speedily!