What it is advisable to learn about Refugia | Reef Builders


A reef tank is totally different from different varieties of tanks in loads of methods, with one of many largest being that almost all reef tanks make the most of a sump to carry the gear and so as to add quantity to the system. An adjunct to having a sump is that a few of us now take this sump one step additional and use the sump, or at the least a part of it as a refugium. 

Curiously the definition of a refugium is an space of isolation through which a inhabitants of organisms can survive by a interval of unfavorable circumstances. Whereas that is partly true, this isn’t what we imply after we say our system incorporates a refugium. First, our refugia are solely remoted within the context that they’re separate from our principal show tanks. Second the organisms that we preserve in them are typically saved there as a way for holding them from being consumed by the tank’s inhabitants and lastly, a refugia is often used as a way for lowering vitamins.

A hang-on-the-back refugium

So what’s the distinction between a easy sump and a refugia? A sump is solely a tank remoted and often beneath the principle show tank that homes all the gear, skimmer, heater, media reactors, and pumps, that assist to keep up the soundness and circumstances in the principle show tank. The refugia is an add-on both throughout the sump itself or as an remoted part the place dwell materials is housed that in a roundabout way assist to supply a profit to the principle show tank. The quantity and sort of dwell materials can range considerably relying on what’s making an attempt to be eliminated or added to the system. These can include substrate, dwell sand, useless sand or “mud”, dwell rock, algae, both Caulerpa or Chaetomorpha, microfauna, and even corals like Xenia or clams. The professionals and cons of every of those might be mentioned beneath.

Miracle Mud

The primary time I ever noticed a refugia, it was not even referred to as that then, was in 1996, once I visited Leng Sy at Ecosystem Aquariums and noticed his “Miracle Mud” refugia system. The interest had solely not too long ago shifted over to utilizing protein skimmers, so I used to be shocked once I noticed Leng’s well-stocked thriving system being run with solely a refugia filled with his miracle mud and Caulerpa. There was no mechanical, chemical or different varieties of filtration, solely a big tank beneath his tank lively. After I say life, along with the mud and Caulerpa, the refugia contained all kinds of microfauna together with amphipods, copepods, worms, and different organisms that thrived within the mud and on the Caulerpa. 

Whereas we didn’t realize it on the time, this method was engaged on a number of ranges to supply for the tank in ways in which we’re solely coming to know. The Caulerpa acted to take away vitamins like nitrate and phosphate, the mud slowly launched hint components into the system and the entire refugia acted as a breeding floor for microfauna the offspring of which washed into the tank serving to to feed the fish and the corals. To this present day, it’s nonetheless one of many extra spectacular methods I’ve seen, particularly contemplating how little know-how it truly used.

From this begin, refugia have advanced into many issues. Most use them as a house for algae of some kind, both Caulerpa or Chaetomorpha, with the aim of utilizing these vegetation as a way for eradicating extra vitamins like phosphate and nitrate. In the course of the early years when this was the aim, most refugia tended to be very giant with the lighting of the refugia being reasonable at finest. Nonetheless, over time refugia have advanced in order that they will now be a lot smaller, however with considerably stronger mild, that may now be supplied by LEDs. With this stronger mild, it’s now potential to have the algae develop a lot quicker and therefore take away extra vitamins extra effectively utilizing a smaller chamber. Consequently, it’s now extra potential than ever to have a refugia be a part of a sump even on a small system.

Along with eradicating vitamins and including microfauna it has now been hypothesized that when rising in optimum circumstances the algae might also assist to supply glucose and/or carbohydrates for the corals and different invertebrates to eat serving to to supply an extra dietary profit for the animals. This has but to be confirmed, but it surely is smart. Another potential advantages of getting a refugia filled with algae is that in some situations the algae within the refugia, which is often a higher-level algae, will outcompete the nuisance microalgaes within the system and thus assist to maintain the show tank cleaner. This can be true, however I’ve solely seen it happen when the vitamins to feed the nuisance algae are in brief provide, when there may be an extra, the nuisance algae can nonetheless thrive even within the presence of a thriving refugia.

Macroalgae refugia may help stabilize pH if managed correctly.

A thriving refugia also can assist to keep up the next pH within the show tank than can be the case when no algae are current. This can be true, however the lighting of the refugia must be managed correctly for this to happen. In any other case, it’s going to at finest assist to stabilize pH or at worst trigger it to drop. Through the years I’ve seen refugia of all sizes with some containing organisms far totally different from what are often seen. On one system containing numerous angelfish and dwell rock, no corals, the refugia was stuffed with Tridacna clams housed underneath brilliant mild. The clams had been getting used to take away the surplus ammonia produced from the big variety of fish. They had been truly fairly efficient and the show of them was fairly attention-grabbing.

For related causes, one other tank I noticed, used a refugia stuffed with frequent brown Xenia to assist take away extra vitamins. It too was attention-grabbing to view with the 1000’s of polyps it contained pulsing as they filtered the water. As attention-grabbing as these had been, probably the most attention-grabbing refugia I noticed was utterly totally different in that it was not lit in any respect, truly, it was blacked out in order that it didn’t obtain any mild, and as an alternative of Caulerpa or different light-loving organisms, it contained all kinds of sponges. These sponges had been used as a way for mechanically filtering out as a lot detritus and organics as they may, so the fabric that often breaks down to supply vitamins was as an alternative consumed earlier than it may achieve this. This too was a really environment friendly technique of filtration.


Whereas there are lots of advantages of getting a refugia, there may also be some detrimental facets as properly. First, whereas a refugia is usually a breeding floor for a lot of good issues it may also be the breeding floor for some detrimental animals as properly, together with some animals that whereas not current within the tank attributable to predation will nonetheless develop and thrive within the refugia. These pest animals embrace aiptasia and majano anemones, hearth worms, vermetid snails, and pest amphipods and copepods. When these pests are seen particularly when they’re first seen they have to be eliminated earlier than the inhabitants takes off.

Refugia can develop into a refuge for pests too, like these Aiptasia.

Along with the opportunity of rising these pests a refugia may also be problematic if energy is misplaced for any size of time and therefore the stream within the refugia is stopped. When this happens a refugia, particularly one containing mud or dwell sand or any substrate can go anoxic, or if the facility is off a very long time anaerobic. When this happens and the facility returns it could actually wash the poorly oxygenated water again into the show tank inflicting points. Because of this, planning ought to be carried out to guarantee that there may be some stream within the refugia ought to the facility exit. Lastly, if the Caulerpa are allowed to develop too profusely they will take away too many vitamins from the water and starve the corals. Because of this, the Caulerpa must be managed, it can’t simply be a set-and-forget state of affairs.

Including a refugia to a system can present many benefits to a tank when carried out appropriately. Whereas it does require some additional planning and gear in the long term it’s my opinion that it’s a actual profit to have one on just about each reef tank. And when deliberate for correctly and managed even the potential shortcomings could be managed readily.

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