Sumps

A sump requires an aquarium overflow box or drilled tank to deliver water to the sump. Water drains from the fish tank to a filter sock, trapping waste. Water then flows through aquarium sump baffles to aerate water and trap waste. Then, an aquarium return pump sends water back to the display tank.

Fish tank sumps usually have several chambers, which may include a protein skimmer chamber, a refugium, or an auto top off (ATO) reservoir. Some sumps have adjustable baffles to set protein skimmer height. A submersible heater and any specialized filtration can be housed inside the sump, hidden from the display tank. Other options include probe holders, cable management, and silencing plates.

As a general rule, buy the largest sump that will sit inside the aquarium cabinet and matches your protein skimmer height requirements.