What Is A Refugium ?

What Is A Refugium ?

Once generally considered to be for large systems only, refugiums are becoming increasingly popular additions to smaller All in One systems, such as the Reef Casa lineup of nano reef tanks.  So what exactly is a refugium?  And why would a reefer choose to set one up in their Reef Casa aquarium?

A refugium is a component of a reef tank’s filtration system that is separate from the main display tank.



Generally reefers will use the refugium to grow macroalgae such as chaetomorpha or caulerpa.  This macroalgae will absorb nutrients such as phosphate and nitrate, which can then be harvested and thus permanently removed from the aquarium.


In addition, a refugium can also be stocked with copepods and can provide a refuge (hence the name) for them to grow and reproduce.  In an All in One system a refugium can easily be set up in one of the rear chambers.


So why would a hobbyist choose to set up a refugium in their reef tank?   In short, a refugium offers a wide variety of benefits such as nutrient control, a place to safely breed copepods that provide a food source for tank inhabitants as well as helping to balance the pH levels in the aquarium.  The most common reason that hobbyists choose to set up a refugium is to control the levels of nitrate and phosphate in the tank.  The macroalgae that is grown in a refugium will out compete the nuisance algae and help to keep the display tank looking great.  When the macroalgae is harvested from the refugium the nutrients that were consumed to grow it are permanently removed.

Aquarists who keep species such as Mandarin Dragonets or Scooter Blennies will often set up a refugium to provide a place for the microfauna required by those species to grow and reproduce.  In this way a refugium can help to ensure a steady food source for some of the hobby’s pickier eaters.  Many of these microorganisms will also help to control things such as diatoms and other nuisance algae.

Finally, a refugium can help stabilize the pH in a tank.  If the refugium light is set to the opposite schedule as the main display tank lights, the pH drop that generally occurs when the lights are off can be reduced, which will help with coral growth and health.  This is probably one of the most significant, and least well known, benefits of adding a refugium.  Essentially a refugium increases the biodiversity of a home reef tank and with this comes numerous benefits and, best of all, they are virtually maintenance free.

A refugium offers a number of clear benefits and because at Reef Casa we want everyone to achieve reefing success we have made it as simple as possible to set up a refugium in your Reef Casa nano aquarium.  Our tanks are designed with a large skimmer chamber that can easily be used to set up a small refugium.  To make it even easier, we now offer the Reef Casa Nova refugium light that attaches easily with Velcro to the back of the rear filtration chambers (just make sure to order the version without the gooseneck mount).  If you have any questions about how to set up a refugium in your Reef Casa aquarium please reach out to us, we are happy to help!