What Does A Refugium Do?

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.

The typical refugium has multiple functions. However, their most basic purpose is to provide refuge for organisms that would be quickly consumed if kept in the so-called main tank. This could be plants, animals or
both. Traditionally, refugia are used mainly to protect and nurture macroalgae and microcrustaceans. These two are mutually beneficial, as a healthy, thick bed of seaweed provides an enormous amount of prime habitat for the “pods” (especially copepods) while the pods keep the “macro” clean of detritus and microalgal films.

The benefits to the system are wholistic. As they grow, macroalgae remove unwanted, excess dissolved nutrients (e.g. nitrate and phosphate) from the water. Particularly when run on a reverse light cycle (day and night cycles that alternate with the main tank), the removal of CO2 during photosynthesis serves to stabile pH throughout the whole system.

The pods help to maintain a hygienic environment by consuming detritus. This can work quite well in a heavily planted refugium because suspended organic matter settles out or gets trapped within the dense macroalgal bed.

Finally, macroalgae (especially highly palatable varieties such as sea lettuce and ogo) are fed out to herbivores in the main tank as the crop in the “fuge” reaches it carrying capacity. Excess pods, both adult and juvenile, continuously spill out from the fuge into the main tank where they may be consumed by various hungry inhabitants. In this respect, what refugia really do is convert bad stuff like excess nutrients, microalgae and detritus into highly nutritious, natural live foods for your fish and invertebrates!
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