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If there is one thing your fish need, it’s filtration. Get this right, and you’re
heading strongly in the direction of success.
T
he filter is the life-
support system of
any aquarium. Fish
produce pollution from
breathing and defecating, and
if not removed or broken down,
that pollution can kill fish as
they are not equipped to swim
and survive in their own waste.
In nature, fish waste products
like toxic ammonia are diluted
by the sheer volume of water or
swept away downstream. In the
aquarium water volumes are
limited and we cannot change
water constantly, so we employ
a bit of engineering and a little
help from Mother Nature to do
the job of filtration.
Benefits
Filtration keeps the water
clear, aerates it in some cases,
and breaks down fish waste.
Without filtration aquarium
water would quickly become
cloudy and smelly. Worse,
your fish could go off their
food, become ill and even
die. Unfiltered aquariums are
fraught with water quality issues
and may cause the untimely
death of any fish.
Filter media
When it comes to filtering water,
it can be done in three ways:
mechanically, biologically and
chemically. Mechanical filters
trap debris and particles in
the water. When they have
trapped lots of debris they
may clog and stop the pump
from working, so they must be
cleaned or replaced regularly.
Common forms of mechanical
filter media include sponge and
filter wool, or floss.
Biological filtration is
perhaps the most important
to the fishkeeper as without it
fish could die from ammonia
poisoning. To filter biologically,
we use porous media with a
large surface area, but that is
not what does the filtering – it’s
what is living on that media that
is important.
Biological media provides
a home for naturally occurring
nitrifying bacteria. The more
media you provide, the greater
the surface area and more
bacteria can live there.
Biological filter media should
never be washed under the tap
as chlorine and chloramine will
kill the bacteria that you need to
purify the tank water. Examples
of biological filter media
include ceramic and plastic
balls or rings. Sponge will
also work as a biological filter
once colonised with beneficial
bacteria.
Chemical filtration is often
used to fine-tune aquarium
water. The most well-known
chemical filter is carbon, or
charcoal. Carbon absorbs
impurities from water and
makes it crystal clear and
odour free. Activated carbon is
better as it is more porous and
has a higher surface area.
Resins are also used as
chemical filters and can be
used to remove phosphate,
nitrate and other organic
pollutants like ammonia. They
can be used alongside other
filter media, and phosphate
and nitrate resins can be used
to control algae.
TIP
NEVER CLEAN YOUR
FILTER SPONGE
OR ANY OTHER FILTER MEDIA UNDER THE TAP AS THE
CHLORINE IN THE TAPWATER WILL KILL ALL THE
BENEFICIAL BACTERIA
. INSTEAD, GIVE THE MEDIA
A RINSE IN THE BUCKET OF
TANK WATER
THAT YOU’VE REMOVED DURING YOUR WATER CHANGE.
Watch that
filtration
Neil Hepworth
Congo tetra