In aquariums, there are different types of filtration: internal decant, external filter and semi-wet filter. The last is not used much.
The internal filter is often present in fully equipped commercial aquariums. In my opinion, they are less efficient, with less flow than external filters. In addition, when the filter media are removed from the internal filters for rinsing, a lot of waste is returned to the aquarium. That’s why I definitely prefer external filters. Their use is simple and effective. For any filter, it is necessary to provide a flow of at least 3 to 4 times the volume of the aquarium per hour.
Each filter, whether external or internal, must be composed of different masses of filtration’s each having their utility:
It helps to retain all particles suspended in water, such as leaf residues. They are foams of different grain sizes and noodles (in red on the drawing).
The noodles will be placed at the beginning, to eliminate the biggest waste (and also to retain bacteria), then a foam with a rather large granulometry, and finally, at the top of the circuit of the wadding for the smallest particles.
Foams should be cleaned regularly to prevent clogging. You just have to rinse them under water, without too much stress not to destroy the bacteria. Especially no hot water, the best is also to use for rinsing the water taken from the aquarium.
She is indispensable. Its function is to fix a large number of useful bacteria that will be used to transform ammonia into nitrites and nitrites into nitrates. Biological filtration masses are in the form of ceramics, noodles, porous stones or pozzolan (in red on the drawing). These masses of filtrations will not be maintained, just a light rinse in water taken from the aquarium to keep all the useful bacteria.
Attention when changing the biological filtration (every year in general, refer to the instructions), it must be done in several times, by third or half to allow the new ceramics to be colonized by the bacteria of the remaining ceramics .
It is only used when needed. It may be, for example, antiphosphate resins or nitrates, an activated carbon for removing drugs. It will be placed above the biological filtration (in red on the drawing).
Some aquarists filter on activated charcoal permanently out of the activated carbon not only absorbs toxic elements but also trace elements present in the water.
Chemical filtration is only momentary and should be discarded as soon as the desired result is achieved.
The regular maintenance of the filter is essential for the good health of the aquarium: once a month is a minimum. Of course you have to do it more often if you see that it gets dirty too quickly. For my aquarium, once a month is more than enough.