Filtration

Basically, there are 3 types of water filtration: mechanical filtration, chemical filtration
and biological filtration.

Mechanical filtration

In mechanical filtration, water is passed through a thin sponge or a screen, which
removes the debris. The size of the debris that can be trapped and the time required to
filter out the water depends on the quality and the density of the material used, as well as
on the power of the pump head. In the course of time, these filters will get clogged and
will need to be cleaned. Thus, mechanical filters help to clear out larger particulate matter
from the aquarium. Under gravel filters are a type of mechanical filters that uses the
aquarium gravel as filter material and trap the debris among the gravel.

Chemical filtration

In chemical filtration, water is passed through Activated Carbon or a natural mineral
called Zeolite. Activated Carbons are used primarily to make water clear and remove
potentially harmful chemical substances. It will remove color and odor producing
substances. Chemical filtration is most useful for removing particles that have got
dissolved in the water and substances that are too small to be removed through
mechanical filters. Usually, it helps to clear the yellow color that develops in aquarium
water over a period of time. Chemical filtration is also very good to remove medicine
lingering in the water after successfully curing a disease in your aquarium.


Biological filtration

Biological filtration uses bacteria that live on gravel, glass surfaces etc to brake down
harmful substances in the water. This is the most effective kind of filtration for reducing
toxic wastes. Fish normally give out ammonia from their gills and in their feces. This
ammonia is toxic for fish. In a natural environment, Ammonia is turned into Nitrite by
one type of bacteria, and the Nitrite is then subsequently turned into Nitrate by another
type of bacteria. Both Nitrate and Nitrate can harm your fish, but Nitrite is much more
damaging than Nitrate. Fish waste products can propagate plant growth in your aquarium,
but it will also propagate undesired algae growth.

Biological filtration will take place in a healthy aquarium without you having to worry
about it, as long as you don’t kill the bacteria by vigorous cleaning or the use of
chemicals. One place where such biological filtration takes places is in the filter of your
mechanical filter and it is therefore very important not to clean this filter in hot water or
using any type of detergent. Clean it cautiously with room temperature water to allow at
least some bacteria to survive in the filter material and start the biological filtration again
as soon as you put the filter back in the aquarium.