Sump
A sump is essentially a large open box filled with water, which will house the vast majority of the equipment or other useful articles. Pumps, heaters, bioballs, and protein skimmers are often housed in the sump. A sump will sit below an aquarium normally inside a cabinet and a return pump will be used to move the water back up to the display tank.

Protein Skimmer
A protein skimmer utilizes a tall cylinder in which air bubbles are pumped into. As they rise the air bubbles attach to organics such as fish wastes, and pull them out of the system as the bubbles overflow into a collection cup and pop; leaving the waste behind.

UV Sterilizer
A UV (Ultra-Violet) Sterilizer uses radiation produced from a high intensity light to kill algae and pathogens in the water column in order to control the spread of disease and limit the maintenance of algae.

Media Reactor
Reactors can house many different compounds that perform different tasks. Some examples would be aragonite, which is used to maintain the levels of calcium in the aquarium, or carbon or other medias which will bind detrimental chemicals in the aquarium like nitrates or phosphates.

Heater
If the tank runs colder than desired, a heater is normally used to regulate the temperature of the water. It is always a very nice and inexpensive piece of equipment to have because a few degrees of temperature swing can be very harmful to the aquarium’s inhabitants!

Chiller
A chiller is an air conditioner for your aquarium! If the tank runs hot, one of these will help maintain a lower temperature. While most aquariums will not need a chiller, the addition of metal halide lights (which produce a lot of heat) sometimes creates the need for one.