With EHEIM biopower you have a high performance internal filter that has never before existed.

It has got its all-round rotatable pumphead, its modular construction and further features from the aquaball concept. 

The special thing about biopower is that it offers multilayer filtration just like an external filter. The closed filter baskets are filled with highly efficient filter medial (e.g. SUBSTRATpro). The inlet basket with filter cartridge for the mechanical-biological prefiltration is located at the bottom. The water sucked in at the bottom is pumped to the top through the various filter    layers and after filtration directed back into the tank.