Refugium Q&A

A refugium is a separate tank connected to your main tank usually used to house macroalgae, live sand and live/rubble rock. It's also important to note that they should never hold animals such as crabs, fish or anything that might decimate critter population. One of the main functions is to protect small critters from the main tank giving them a shelter to reproduce without the threat of being consumed. The idea is to have the refugium give a slow supply of pods to feed the main tank to be consumed by corals or fish. Usually the pods are able to survive the trip to the main tank even after going through the pump.

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What other functions does a refugium serve?

Another main function of a refugium is to provide a space to grow macroalgae. Macroalgae serve a very important role in removing excess nutrients (mainly nitrates and phosphates) from the system. They help prevent high levels of nutrients which may have a negative impact on the corals and fish. They also help prevent micro algae such as the dreadful hair algae. Macroalgae are generally much easier to control than micro algae and thus it's preferred. However, just because you have a fuge housing macro algae does not mean you can go on an all out feeding frenzy. Water changes and maybe even skimming are still important.

Refugiums can serve the function of stabilizing pH when the main tank light is off. Generally when the lights go off in an reef aquarium the pH begins to drop, which is not a good thing as it's preferable to keep pH stable at all times. The technique of switching on the fuge light when the main tank light is off is also known as putting the refugium on a reverse light cycle. Generally you can set the light on the refugium to turn on one hour before the main tank turns off and turn one hour after the main light turns on. There is debate whether keeping the lights on the fuge 24/7 is beneficial. I prefer to give the plants a resting period as it would in the ocean. However, there are generally no problems with keeping the lights on 24/7 especially if you have Caulerpa.

Here is a list of other benefits of having a refugium:

-A good place to hide your heater and thermometer

-Increases total water volume which helps water stability. Tanks that serve the purpose of holding extra water are known as sumps.

-A place to hold live sand if you wish to go bare bottom

-A place to give beneficial critters a chance to thrive without threats from fishes and corals.

What type of macro algae should I add in a refugium?