
11
It is, ho ever, necessary to increase the metabolism of the bacteria so that they can reduce
enough nitrate. For this reason, the nitrate removing bacteria have to be fed ith organic
substances. The food Denimar contains organic substances that can be used completely by the
bacteria. The only aste product is CO
2
.
The flo rate through the Nitratereductor is very slo . This is the main difference to other
aquarium filters here the ater is often treated once per hour or even more often. The ater in
the Nitratereductor should have a retention time of 4 hours. It is, ho ever, sufficient to treat it
once per eek. If the filter is adjusted correctly, the ater leaves the filter nearly free of nitrite and
nitrate.
4. Description of the Nitratereductor
The AB Aqua Medic Nitratereductor consists of a reaction vessel (1) of 10 l volume. To provide
surface material for bacteria, the filter is filled ith AB Aqua Medic Bactoballs (2). They create an
ideal microclimate for denitrification.
To avoid dead zones, the ater is recirculated internally in the Nitratereductor. A recirculation
pump (7) is placed in the top.
In denitrifying filters, especially in units here the ater has to pass through a long ay, it can
occur that there is no even flo in the filter. Zones ith a very lo redoxpotential are created
here hydrogensulfide is produced (the filter starts to smell badly). On the other side, zones ith a
rather high flo may arise here nitrate is reduced only to nitrite. In each case, the conditions
vary in the different zones of the filter and it is nearly impossible to find its right orking point.
These unpleasant effects are avoided by the construction of the AB Aqua Medic Nitratereductor.
The recirculation ensures a complete mixing and the same redox potential level in the hole filter.
Zones ith a very lo redox potential and the production of hydrogen sulfide are avoided.
The redox potential can be used for the control of the filter. The effectivity and the reliability of the
filter can be increased.
Connections
The follo ing connections are located at the Nitratereductor:
1. Inlet (5): There, you can connect a 6 mm air tube. At the inflo , you find an adjustion valve to
adjust the flo rate. The best value is approx. 1 – 1.5 l/hr (approx. 1 drop per second). The
adjustion at the inflo causes a delay until you can read the adjusted drop number at the drop
counter (14) at the ater outlet. The drop counter is mounted inside the aquarium, close to the
ater level. If the flo rate is regulated in the outlet, the valve may not be closed completely in
order to allo produced nitrogen to escape. During the start phase in the first eeks, the outlet
valve should stay completely open. The inlet has an internal elongation that prevents that gas
enters the inlet tube.
2. Feeding: Through this opening (4), you can inject Denimar-Po der ith a syringe to enhance
denitrification. Dissolve the po der beforehand in some ater. The valve has to be cleaned and
closed after every feeding.
3. Redox electrode: Through this opening, (17) you can put the pressure resistant ORP electrode
ith standard thread (PG 13,5) Aqua Medic No: 220.18.
4. Outflow to aquarium (14): There, you can connect an air tube 6/4 mm, preferably a black
one to prevent algae gro th.
5. Set-Up
The Nitratereductor is a hermetically closed system. The produced gas (nitrogen and CO
2
) can
escape through the ater outlet. For this reason, the outlet should never be completely closed,
because an eventual overpressure may escape through the ater inlet and interrupt the inflo .
The Nitratereductor has to be placed in a ay that the ater can flo off either directly back into
the aquarium or into the filtration chamber. In a sea ater aquarium, it is advantageous if the
outflo ing ater is flo ing into the inlet of the protein skimmer or the trickling filter. In the protein
skimmer, the ater is saturated ith oxygen before it flo s back into the aquarium.