The addition of a refugium can stabilize your marine ecosystem by providing nutrient export with the growth of macro algae as well as create an isolation area for new or injured fish. The idea when erecting your first refugium is to establish an area for natural denitrification. This aids both tanks being linked to a common water source and a deeper sand bed makes this possible. A refugium can also be a place where certain inverts such as Seahorses, Peppermint Shrimps, Copepods & Amphipods and other delicate species need a place to call their own, a "quite place"; otherwise they would not last long at all in a community tank. Isolated, but connected to the main display tank, the refugium allows for common water filtration while at the same time keeping more aggressive fish from impacting it.