Internal Aquarium Filters
Submersible or internal filters can be used in a way that no other filter can and are designed for entirely different use than another filter type. These submersible filters are placed entirely in the water with no outside parts except the power cord. These filters can be placed on the bottom of an aquarium horizontally, and they can be used in shallow water for half filled turtle or fish aquariums. Fluval and Duetto are two of the big names in internal filtration, offering chemical, biological and mechanical filtration in each of their units.