Blueprint of a mixed reef system
Two tank system
A typical system usually employs a combination of two tanks. One for the animals and one for water treatment. The upper tank is often called the display tank (DT). The lighting system hangs over (or sits on) the display tank. The bottom tank (aka sump) is usually placed in a cabinet to conceal the gear and wires.
Animals (fish, corals, etc.) and liverock are placed and arranged in the display tank.
Water drains via an overflow from the display tank down to lower tank (often called the “sump”) where it is treated and then pumped back to the display tank in a continuous loop. Other devices (protein skimmer, chiller, heater) to aid water treatment are often inter-connected in the sump area, or in a separate room if available, the “fish room”.
Like a swimming pool setup. A place to swim and an area for water filtration, equipment, and treatment.
A space directly below the display tank is often used for the sump and enclosed to hide from view the sump and related water treatment equipment. The cabinet (or stand) also provides a top shelf to support the display tank.