What does a refugium do?
Refugia continue to become more and more popular in the marine aquarium hobby. This is in large part because of a growing reliance on natural water filtration/treatment methodologies. But, mainly, this is because they actually work.
In most cases, the central function of a refugium is to offer a place for organisms that would typically be consumed or not given the right environment in the display part of the aquarium. This can refer to several kinds of organisms, but most commonly it is for microscopic crustaceans such as copepods and macroalgae. Having a refugium enables hobbyists to give specific conditions for macroalgae. Usually, the largest difference between a refugium and the display in terms of conditions is the lighting. Macroalgae prefers different lighting than what corals prefer. The great thing about all this is that the macroalgae and copepods help each other out. The macroalgae makes the perfect breeding grounds for copepods, while the copepods keep the macroalgae clean of detritus and microalgae.
Why bother with any of this? Well, refugiums are highly practical. While many hobbyists enjoy them for their looks and intrigue, refugiums serve many benefits to a reef system. Let's start with macroalgae.
While macroalgae is a great habitat for copepods, its primary function is to remove nutrients (nitrate and phosphate) from the water. This will make it more difficult for nuisance algae to grow. It is sort of like fighting fire with fire. The difference between macroalgae and nuisance microalgae is that macroalgae is manageable and does not easily spread or take over aquariums. Chaeto and Sea Lettuce is best for this.
Additionally, macroalgae helps to stabilize pH by removing CO2 during photosynthesis. This works especially well when the refugium lighting is run opposite of the lighting on the display.
What about copepods? Why bother having those little white dots in your aquarium? There are several benefits to having copepods in your aquarium. Usually, hobbyists add copepods for feeding fish, specifically finicky fish. The problem is that fish can quickly wipe out the copepod population in a display tank. The Mandarin Dragonet, for example, can eat thousands of copepods in one day. While a large enough display with enough rocks can grow a large population of copepods, a refugium provides a place where copepods can breed without getting eaten. As the copepods populate the refugium, they will also flow into the main display from the refugium. This encourages a more stable population of copepods to feed a finicky fish.
Copepods also benefit those without finicky fish by eating detritus and microalgae. They are especially good at getting into those small places that nothing else can get to. Copepods are also great for feeding corals. As mentioned before, copepods benefit a refugium specifically by keeping the macroalgae clean of detritus.
Another great use of refugiums is to grow macroalgae to feed fish. Many aquarium fish such as tangs, blennies, angelfish, and many more need some sort of vegetation in their diet. It is important, for tangs especially, for fish to get greens in their diet. This helps keep the fish healthy and free of disease. It also promotes brighter colors, which of course is very important for us hobbyists. The macroalgae is grown in a refugium, and then, once it grows too large, it is trimmed back. The trimmings are then given to the fish. This way, the macroalgae is taking nutrients from the water and feeding the fish at the same time. Refugiums are amazing for keeping your fish fed, whether its a dragonet or a tang! There are several macroalga that are palatable for fish. Sea Lettuce and ogo are some of the best kinds. Here
you can find other macroalgae species.
For a lot of saltwater hobbyists, refugiums are crucial to their aquariums for doing the functions talked about above. Are there other ways to do those things? Are there other ways to grow macroalgae, remove nutrients, and feed fish? Yes, of course there are. A refugium may not be for everyone. However, what makes refugiums so great is that they can provide solutions to several different aquarium problems at once. Also, there are so many different ways you can implement a refugium, depending on what you want it to do.
If you're interested in adding a refugium to an existing tank or implement one in a new build, checkout the Ultimate Refugium Starter Pack
from AlgaeBarn. This pack will provide everything you need biologically to start your aquarium. Also, check out these premium refugium lighting
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