Several years ago, FAMA and other aquarium periodicals brought the refugium to our attention. There resulted a flurry of "how-to's" and "why-for's" that occupied many pages in many magazines and continues to be the subject of new inquiries. So, from a non-scientific and hobbyist's perspective, let's talk refugiums!
Essentially, a refugium is nothing more than a refuge from predation. Sessile inverts and other delicate species need a place to call their own and the advent of the refugium was just the ticket! Isolated, but connected to the main display tank (see diagram above), the refugium allows for common water filtration while at the same time keeping more aggressive fish from impacting it. Follows is a diagram showing a simplified refugium setup. Notice how the water is delivered to the unit and how it drains back into the display tank and/or sump. I'll take this opportunity to point out that a true refugium is NOT a reverse photosynthesis device! Nope, those are another animal altogether! True refugiums are meant to be SEEN as is the main show tank! Reverse photosynthesis arrangements are meant to be installed in a sump, beneath the display tank and are a means of primary biological filtration. Not so the refugium!
The focus here is to provide a "quiet" zone for Seahorses, Peppermint Shrimps, Copepods & Amphipods and other denizens that would otherwise not last long at all in a community tank. While benefiting from the improved water quality that most reef systems provide, this isolation allows for spawning in our shrimps or other animals, as well as providing a nice sand bed for beneficial worms and other sifters.
When contemplating installation of a refugium several factors should be considered. First, where are you going to set it up, or place it? Most agree that placing the refugium as close to the main tank as possible is the way to go. Many aquarists have simply set a 10 gallon aquarium on a table next to it's big brother. This works, but requires a water return pump unless draining back into a sump or main tank. So where does the water supply come from, and where does it go?
Next Page > Building A Refugium - Plumbing The Refugium