Aqua Medic NR 400 Manuel D'instructions page 10

04. Y-piece (connection for feeding syringe and water)
05. Adjusting valve for waterflow
06. 6/4 mm tube (feeding and water inlet)
07. 8/6 mm tube (water outlet to drip counter)
08. T-piece for bypass
09. Pressure side of circulation pump
10. Filter tank or aquarium
11. Circulation pump
12./13. Power plug
14. Aquarium
2. Theory
Nitrate is coming into the aquarium via 2 different ways:
with tap water, with every water change or with the replacement of evaporated water
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by biological reactions in the aquarium
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These biological reactions are responsible for the farmost biggest part of the increase of the nitrate
level.
How is nitrate produced in the aquarium?
When the animals are fed with dried, living or frozen food, proteinaceous substances get into the
aquarium. These are the basics of the diet for the animals. A big part of the nitrogen from food is
however, excreted into the water. This nitrogen is metabolised by bacteria, living in the aerobic
filter via the toxic intermediate substances ammonium and nitrite to the less toxic nitrate. These
biolochemical reactions take place in the presence of oxygen:
The bacterium Nitrosomonas oxydizes Ammonia to Nitrite, the bacterium Nitrobacter the Nitrite to
Nitrate.
Ammonium + Oxygen ----- > Nitrite + Oxygen -----> Nitrate
(Nitrosomonas)
In most aquaria, nitrate is the endproduct of bacterial metabolism and accumulates in the water.
Only higher water plants and algaes are able to remove this nitrate from aquarium water.
What is the effect of nitrate in the aquarium?
Overfertilization/etrophication: The aquarium is overfertilized, the algae growth increases and
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cannot be controlled anymore.
Toxic effects to the animals: Many invertebrate animals in salt water tanks are very sensitive to
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higher nitrate levels.
3. Working principle of the Nitratereductor NR 400
In the Aqua Medic Nitratereductor the water is treated anaerobically. In the absence of oxygen,
many bacteria are able to use nitrate as a substitute for oxygen for their metabolism.
2 Nitrate ----> nitrogen gas + 3 oxygen
2 NO 3 ----> N 2 + 3 O 2
Oxygen is used for metabolism, the nitrogen is excreted into the water. Nitrogen gas is a natural
compound of water and totally harmless.
It is, however, necessary to increase the metabolism of bacteria so that they can reduce enough
nitrate. For this reason, the nitrate removing bacteria have to be fed with organic substances. The
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(Nitrobacter)