Refugiums, What You Need To Know:

Some Refugium Education

Reef Aquaria have become more complicated over the time. The reason for this is that there is currently a greater awareness of, and emphasis on the base of the natural marine food chain.
The reason for this is to control what goes on in your tank.
To make this more easily understandable: The upper base of the chain is usually tiny, intermediary organisms. This ranges from protists to microcrustaceans like for instance, Copepods.
At the lower base, and I actually mean at the bottom, you will find your primary producers.
The lower base producers are autotropic bacteria, algae and plants.

The autotrophs produce their own food energy and biomass from the inorganic sources of energy such as from light, and inorganic carbon, such as carbon dioxide. This food source is fed on by the intermediary critters. It is then transmitted up into the food chain as the critters then gets consumed by the predators, such as fish.
The larger fish would then again consume the smaller ones, thus the nutrients are recycled with the greatest of efficiency.
During this time, waste products, primary from the consumers are re-diverted back into the tank, this is where your Refugium will come into use.

A Refugium is an auxiliary tank that links up with your main display tank. Your Refugium will serve as a refuge for your primary producers and consumers (such as pods)
Copepods will proliferate in a Refugium because they are safe and out of reach from large herbivores. Pods will reproduce and eventually will be carried from the Refugium to the main tank.
This is how your corals and fish will be fed on a continuous basis. With microalgae in your Refugium, your aquarium water quality will improve, and it will support maximum pod populations.

WHAT IS THE DIFFERENCE BETWEEN A REFUGIUM AND A SUMP?

Both these units serves as reservoirs for re-circulating aquaria systems. Plumbing for both these units are also basically the same. A Refugium might contain a sump and vice versa, but that, is where all similarities ends.
The distinction between these units lies with their fundamental purposes. Sumps are mainly used for the centralization and compartmentalization of filtration and the monitoring of equipment. Refugiums are primarily used to promote the growth and the reproduction of animals such as copepods and plants such as macroalgae.

SO WHAT IS A REFUGIUM?

Refugiums, usually consists of a second tank. It will have sand or gravel. You will usually find seaweed, like Chaetomorpha, that grows over the bottom.
This is an ideal environment for your copepods to thrive in. Not only will they find shelter in the algal mass, but it also provides a habitable surface area.
The most important of this all, is that your copepods can grow and multiply in a predator free environment.
This is ideal for population growth of your copepods that eventually will spill over into the main tank.
YOU MAY ASK WHAT BENEFIT INSTALLING A REFUGIUM HOLDS FOR YOU.

Many Reef Keepers ask the question if installing a Refugium is really worth the time, effort and finances.
Here I will discuss the 5 top reasons, why you should consider it.

NITRATE CONTROL

Refugia has sand and gravel beds that hosts highly beneficial bacteria that will metabolize nitrate.
The growth of nuisance algae are limited when lowering nitrate levels. This is particularly beneficial where the main tank has a bottom with little or no cover. The Refugium, usually has a deep bed and this adds tremendous amounts of habitat complexity to your system.

JIP, EVEN MORE NITRATE CONTROL

Nutrients, such as nitrate are consumed by Macroalgae as they grown. This results in competing with the bad microalgae that will from unsightly films against your tank sides. Microalgae are therefor used as a vehicle for the nutrient export so that the unwanted algae can not grow.
As soon as a point is reached where the good algae mass has grown large enough to fill all the confines of the Refugium, it starts to shade itself and growth rates decline. This is the point where you need to harvest and discard the mass.

A NURSERY?? REALLY!!

The macroalgae not only helps maintain good water quality, but is an excellent habitat for microcrustaceans like copepods. Macroalgae love pods, as they keep them clean and enable them to capture as much light as possible. There comes a point where the older plant material will start to deteriorate and decay, and your copepods will feet on this waste.
Seeing as no fish is present to eat them and that their living conditions in the Refugium is perfect, copepods will be extremely productive. So yes, see a Refugium as your copepod nursery.
Copepods are important in an aquarium food chain. I cannot overstate enough, how valuable they are to act as intermediaries, to turn the bad stuff such as algae and organic waste into the most super nutritious live food for your fish and corals.

SEDIMENT

It is best to have your organic muck in your Refugium, than visible in your display tank.
When your Refugia is planted quite heavily, they will act as a sediment pools. That is when the particulate organic matter that passes into the Refugia from the main tank. It happens that the muck stays in the Refugia due to water slowing as they pass through the dense seaweed. Copepods will subsequently consume this detritus. They are also consumed by other deposit feeders.

LAST BUT NOT LEAST, WATER VOLUME GAIN

By adding to the overall water holding capacity of your aquarium, your giving your livestock breathe room. Any system, fully matured or freshly set up, benefits for additional water volume.
With a Refugium you will not only add volume, but are diversifying the larger captive ecosystem, which allows for more biological diversity.
A Refugium is seen as a hot spot for biological activity, where waste products are converted to copepod and macroalgae biomass

CONCLUSION

So, ask yourself, should I set up a Refugium in my tank?? The answer is a simple and straight forward YES.
If you have the space and the means to do so, then go ahead, it is highly beneficial.
With all the benefits you will get from doing so, stop to try and argue yourself out of it.
Add it and reap the benefits.