Abstract: An aquarium filtration system using airlift to circulate water within the living area to display aquatic organisms, water rising up through the bottom gravel, the gravel providing biological filtration. The living area of the acquarium is free from mechanical obstructions and rising air bubbles. A relatively inexpensive air pump generates the air lift, for circulating water within the living area. Water is removed at the water's surface and thereafter mechanically and chemically filtrated. A protein skimmer device is provided as an integral part of the air lift and mechanical filtration chamber to remove dissolved organic and inorganic compounds.