Refugiums by definition are a safe haven or hideaway, or an area or place for wellness or recovery. For aquarium purposes, a refugium is an isolated area or system, which shares the same water as the main body of water in the aquarium system. Refugiums are available in several forms, ranging from a simple hang on design that is simply an isolated area in the aquarium, to a hang on unit that is external to the aquarium and circulates water with a water pump. Refugiums can also be in the form of a remote sump style design, or also as an incorporated compartment in a more complex reef sump aquarium filter.

Refugiums are typically used to house plants or macroalgaes that remove nutrients from the water, that would otherwise be unsightly, or eaten by herbivorous fish in the main aquarium. Growing plants within a refugium can greatly improve water quality, by exporting phoshates and nitrates as a food supply for the growing plants. Plants grown in the aquarium can be harvested, and used as a food source for animals in the aquarium. Refugiums can also be used to house delicate scavenging invertebrates, small coral fragments, small or young fish, live rock, live sand or injured animals. Refugiums can also serve as a breeding area for many beneficial microorganisms that can supply planktivores in the main aquarium with an additional food source. Refugiums are a great addition to the marine aquarium, as an additional and natural water filtration component.

Interested in other types of aquarium filters? Check them out here.