Expand Your Saltwater Tank With a Refugium

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While some aquarists are adamantly against the use of refugiums in saltwater systems, they provide many benefits to a tank. The pros of using a refugium drastically outweigh the cons, and while a refugium is in no way an absolute necessity, it can be a rewarding addition to any saltwater system.

What is a Refugium?

A refugium is basically an extension of the main aquarium, and can be used in either fresh or saltwater tanks. The refugium adds water capacity to the main tank, allowing for a greater turnover of water within the system. For example, if the main display aquarium is 125 gallons, and the refugium is 55 gallons, you now have 180 gallons of water.

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A refugium means more than just extra water in the system. It can have several different uses to benefit the display tank, as well as standing on its own. One of those uses is by using a deep sand bed to increase the amount of denitrification. As with any aquarium system, nitrites and nitrates can become harmful to the inhabitants of the tank if they reach high levels, and the sand bed allows for beneficial bacteria to grow and decrease these potential hazards.

Another use for a refugium is to house macro algaes, which are large species of algae that aid in absorbing nitrates and phosphates from the system. One of the more popular varieties is chaetomorpha because it grows quickly and is easy to trim. It also offers an excellent place for copepods and amphipods to hide in, as they make an excellent food source.

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Refugiums can also be a built-in fry tank if you are a breeder. They can also be used if your fish spawn on their own and you would like a safe refuge for the fry to grow until they are large enough to be in the main tank, or to be sold. Additionally, the refugium can be a great place for an injured fish to heal or for a naughty fish to take a time out from the main tank if it’s been overly aggressive.

Another use for a refugium is to grow fragged corals in until they are ready to be sold or added to the display tank. Since refugiums are generally smaller in volume than a display tank, it can sometimes be easier to light the tank, so corals have an easier time growing.

Some people make refugiums into a secondary display tank, where it is just as beautiful as the main tank. They stock and decorate it just as they would the display tank, and can keep different species of fish and corals in it that could not cohabitate in the main tank. It offers the opportunity to have two tanks, but only run one complete system as far as water testing and quality goes (as long as the inhabitants of both have similar requirements).

As you can see, refugiums can be an amazing addition to any saltwater system. While there are some arguments against using them, generally speaking they provide many benefits to the overall system and can be just as much enjoyed as a single tank alone.

summerSummer Davis is the mom of three kids, four dogs, and several tanks of fish. She boasts a passion for all animals, whether they are in the water or on land. This fish aficionado has kept many different species in her time, but holds a special place in her heart for wild and domestic bettas. When she’s not talking about fish, Summer “spins” her extra time as the director of a baton twirling organization.