Page 75 - Koi Net - On-Line Koi Magazine - Issue 92

Algae doesn’t need much explanation. Algae can use I don’t even need to find evidence for this first standard
Ammonia and nitrate to grow and thus reduce the level
of these substances in the water. The floating algae are
usually prevented/killed with UV lamps and the blanket
algae we extract from our ponds, or we create shade
making it a lot harder for the algae to grow. If you have
more algae as autotrophs and your Ammonia level in the
pond (with some sun) goes up, then you get algae growth.
Thus remain the autotrophic and heterotrophic bacteria
but actually also two other routes which were not
discussed in this article because they did not apply here.
There are also routes without oxygen namely
Denitrification and Anammox. In the next article these are
described in more detail.
First the standard Autotroph bacteria. The basis of
Nitrogen Flow (no ‘Cycle’) like it is always learned and
taught in the Koi world. As is known, nitrification and the
degradation of nitrite by Nitrosomonas and Nitrobacter
among others convert Ammonia to nitrate via nitrite (in the
following diagrams). Degradation to Nitrite by bacteria
from Nitrosomonas, Nitrosococcus, Nitrosolobus,
Nitrospira and Nitrosovibrio, breakdown of Nitrite by
Nitrobacter, Nitrococcus, Nitrospira and Nitrospina. These
processes give the bacteria energy to continue to do
everything in the bacterial cell.
A schematic overview of most processes
looks like this:
The Nitrogen Cycle
N org NH 4 + NO 2 - NO -
³
NO
N 2 O
N 2
Ammonia Oxidation to Nitrite (Nitritation) Complete Ammonia Oxidation to
Nitrate (Comammox)
Nitrite Oxidation to Nitrate (Nitratation)
Anammox Process Dissimilatory Nitrate Reduction
to Ammonium (DNRA)
Denitrification
Nitrogen Fixation
Intermediates for Nitritation, Comammox and Anammox are not depicted.
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part as the evidence is in previous articles. It is well-
known as the effect that arises at the start of a new
pond or growth tank. First, an Ammonia peak is
measured, then a Nitrite peak, and then a Nitrate peak.
Start-up Curve for a Biological Filter
TAN NO ² NO ³
Biofiltration
Nitrification
Nitrification
15
10
Concentration (ppm)
Removal Rate (g/m 3 per day) 5
0
0 7 14 21 28 35 42
Time (Days)
Recirculating Aquaculture Systems Short Course.
The Ammonia peak comes after 14 days, followed by
nitrite on 28 days and last, the nitrate really rises from
21 days onwards higher as the nitrite peak decreases.
Recently, well, at the end of 2015, a new addition to this
became known. In Nature, December 2015 it is
described that there are Nitrospira subspecies that
breakdown Ammonia and nitrite to nitrate at once. And
they do not prove rare but were found in many places in
nature. They were called Comammox, complete
Ammonia oxidiser. Interestingly enough, these bacteria
do not excrete any nitrite, this step is skipped. This
subgroup of Nitrospira was then found in different filters
and wastewater treatment systems and therefore
certainly proved not rare. According to the authors, it
seems more that there is a kind of balance in those
biofilms between the different Nitrospira and other
Ammonia users, but it was always present. In one of the
measurement results, 43-71% of the Nitrospira found
present were Comammox.
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