Why should you add a refugium and macroalgae to your saltwater aquarium setup?
There are a number of terrific benefits to including these components, such as better nitrogen control, opportunities to add
more species of fish, better biodiversity and keeping nuisance algae at bay.
What Is A Refugium?
A refugium, or "fuge", is a secondary tank attached to the main tank. Although it is a separate space, the
refugium shares the water supply of the main tank. It is typically about a tenth the size of the main tank.
Some people choose to display the refugium since it can have an interesting appearance of its own.
Others choose to house it in a cabinet beneath the main aquarium. Some refugiums attach to the back
of the tank. Fuges may have their own light supply or share one with the main aquarium.
Here are some of the uses for a refugium:
- Assisting in cycling the main tank to keep nitrogen levels lower
- Separating an injured or sick fish from the main population until healed
- Growing macroalgae
- Raising copepods and amphipods to feed your fish
- Improving aquarium biodiversity for corals and fish
Macroalgae help manage nitrogen and other chemicals, which keeps the water healthier for your fish.
Beneficial macroalgae like Chaetomorpha (spaghetti algae) or Ulva (sea lettuce) help keep nuisance algae under control. Herbivore fish and copepods also eat them as a food source.
Refugiums Provide a Refuge and Improve Biodiversity
Since a refugium adds about 10 percent more water to your entire aquarium system, it helps control
nitrogen and other chemical levels more efficiently. Plants and macroalgae in the refugium also help
take up nitrogen and add back helpful nutrients.
Sometimes, a fish may become ill or injured. Placing the fish in the refugium keeps it in its regular water
supply but separate from the main fish population so that it has time to heal without being harassed by
The fuge can also serve as a nursery for growing your own amphipods and copepods, commonly called
"pods". Growing copepods in the refugium prevents the fish in the main aquarium from consuming
them all before these pods can reproduce. These plankton are used to feed more delicate, difficult to
feed fish like seahorses, Pipefish and Mandarin Dragonets. Pods are also an important part of the marine
ecosystem. Adding these plankton to the aquarium system helps improve diversity in your saltwater fish
Most aquarium owners find algae to be a nuisance. However, some macroalgae like Chaetomorpha,
also called "chaeto", and sea lettuce (Ulva) help the saltwater fish tank by absorbing nitrates and
phosphates. This keeps the water healthier for your desired fish.
Chaeto and sea lettuce provide food for copepods and amphipods. These macroalgae also give the pods
Caring for sea lettuce or chaeto is very easy. They can float or tumble in the refugium. They do best with
medium to high lighting and medium water flow. They prefer light in the 5,000 to 10,000K temperature,
or the daylight range. Trim and turn the macroalgae weekly to prevent fragments from clogging your
pumps or overflows.
By adding beneficial macroalgae and a refugium to your saltwater aquarium or reef tank, you'll be
improving the diversity of your system. This keeps your fish and coral healthier. For more information
on copepods, refugiums, and macroalgae, contact OC Reef today! You can reach us by using the contact
form online or by calling 949.429.8034. We'll be happy to answer any questions you may have.