Aquarium Sump Filtration is commonly used in saltwater aquariums. There are several styles of aquarium sumps. Refugium filters commonly include aquarium socks aka micron bags. Refugiums will also include a refugium section for many uses. ex: addition of Chaeto Algae or Live Rock. A protein skimmer section usually follows along with the final pump chamber. Other aquarium sumps can be wet dry filters, protein skimmer sumps or any mixture of different chambers. As you can see the term aquarium sump has a large variety of filter types.