Internal filter
Filter positioned inside the aquarium, ideal for small and quarantine aquariums. Economical and simple but with limited filtering volume.
Detailed explanation
The internal filter is a submersible device with a filter sponge. It is the simplest and cheapest solution. Ideal for quarantine aquariums and for breeding fry.
Air sponge filters are the most basic version. An air pump pushes bubbles through a sponge creating a gentle flow. Perfect for breeding aquariums because they do not suck up the young.
For quarantine aquariums the sponge filter is ideal: the sponge can be kept maturing in the main filter and then moved.
Internal filters are almost never used in marine aquariums. The sump with skimmer and live rock provides superior filtration.