The
Aquarium Nitrogen Cycle
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Lets talk Science for a
while......To keep fish you
need to be able to keep water and to keep water
as it should be you need to understand the
aquarium nitrogen cycle and how all the
different elements of the nitrogen cycle fit
together and change the water quality in your
aquarium. |
The
Aquarium Nitrogen Cycle takes place in
any body of water and is
simply nature's way of dealing with fish waste products.
The potential problems start when man intervenes and starts to
mess with the environment and you will not see a
better example of a false un-natural environment than an
aquarium. Most aquariums are trying to imitate a stream
or moving water. In a stream the volume of water per fish
is generally much greater than an aquarium so their waste
products are easily dealt with by the nitrogen
cycle.
In a confined
environment such as an aquarium you need to monitor things and
give the nitrogen cycle a helping hand every now and
again.
Three of the
parameters which are most important to monitor within teh
aquarium nitrogen cycle are ammonia / ammonium, nitrite and
nitrate. These will build up in your tank simply as
a result of putting fish in it.
Ammonia
and Nitrite are poisonous to fish even at low
concentrations. When you feed your fish the food
will be converted into ammonia either by the fish eating it and
excreting waste or by uneaten food decomposing in the
substrate and causing ammonia. Whatever happens the end
product of feeding your fish is Ammonia and without an
effective biological filter the Ammonia levels in the tank will
quickly increase until the fish become unwell or
die.
Fortunately for
Aquarium Keepers there are friendly bacteria (called
Nitrosomonas) that start to break down and convert
Ammonia into nitrite as part of the aquarium nitrogen cycle. The
bad news is that Nitrite is still poisonous to fish so we
also rely on the second type of friendly bacteria (called
Nitrospira) that then break Nitrites down into
Nitrates which are a much friendlier chemical as far as
fish are concerned.
Nitrates are nature's
fertiliser. Once the bacteria have done their job the
water will contain Nitrates which are removed from the water by
plants as part of their natural growth process. As algae
are very simple plants, if you allow the nitrate levels to
build up you may well end up with an algae bloom or 'green
water'. Some aquarium plants are better than others at
taking nitrate from the water.
The
balancing act that you need to master is to make sure that
there are enough bacteria in the system to convert the ammonia
to nitrites and to convert the nitrites to nitrates. The
nitrate are removed from your tank either through plant growth
or through partial water changes. Whenever you are forced
to cut back a fast growing plant, just remember that you are
removing nitrates from the tank along with the
cuttings!!
Remember......When you first
set up your tank there are unlikely to be any good nitrifying
bacteria in the water. It is important to cycle your tank
to build up the correct balance of these bacteria in both the
filter and the substrate to get the nitrogen
cycle working effectively. Whilst this is going on there
will be peaks in Ammonia, Nitrites and Nitrates all of which
can be harmful to your fish so make sure at the start that you
are checking nitrate levels and doing water changes when
needed.
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