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Setting Up Your Saltwater Refugiums

Refugiums are a popular, and important, component to a thriving reef system. As the name suggests, it is a refuge. A typical refugium is an area, usually in the sump, for copepods and beneficial critters to live and multiply without fear of predation by the fish in the display.

The ‘fuge is also a good place to grow macro-algae for nutrient export, it can also be a separate area to grow out frags with a proper light. Let’s discuss all the options you have to set up a refugium that you will enjoy.


Clean Chaeto macroalgae

Chaeto is one of the most common macroalgae used in refugiums.

Chaeto is great for nutrient export, it grows fast and uses nitrates and phosphates in the water for growth. If you intend to use macros in the ‘fuge, adequate light is essential for growth. A lot of hobbyists use a red light such as the Innovative Marine ChaetoMax.

The red spectrum grows algae much better than a reef light which has blues in it. Warm whites and reds are probably the two best options for lighting a refugium.

Some other macroalgae are Ulva, Gracilaria, Caulerpa. There are plenty of other varieties too, like Halimeda, which is a green calciferous macro.

Herbivore fishes like Tangs and Rabbitfish love macros. You can use the refugium to grow macros to feed your fish – nothing like a source of fresh live food.


Tisbee copepods

Some popular varieties of copepods are Tisbee, Apocyclops and Tigriopus. A combination of all 3 is great, but any one of them is fantastic by itself as well. Copepods feed on phytoplankton and detritus and will readily multiply in the refugium. You do not need to light the refugium if you are not intending to have macros in it. Copepods do fine with just some sand and/or rubble to cling to.

Seeding the refugium with copepods is a good idea.

Hang-On-Back Refugium

Hang-on-back refugium for aquarium

If you don’t have a sump, you can install a Hang-On-Back refugium to get much of the same benefits to your system on a smaller scale.

Although it has a small area, it is still plenty to grow chaeto and also to house some copepods. Similar to a HOB filter, there is a pump to pull water in and pump it back out. Macros will utilize the nutrients in the water and the light that you provide to grow.

Frag grow-out or Coral repository

With extra space available in either a sump compartment that is set aside for a ‘fuge, or a HOB refugium, you can do much more than just grow pods and macros. Corals growing like a weed? Frag them and set them in the ‘fuge to heal.

A lot of folks use Xenia for nutrient export. Throwing a stalk of the coral in the ‘fuge and watching it grow in the refugium is a good way to enjoy this pretty coral without the threat of it overtaking your display.


You can put rogue crabs in there. It can be a fish time-out for bullies. A new fish is usually bullied and scared. You can use the ‘fuge to condition the fish and ensure it is eating before introducing it to the display.

Whatever the purpose of your refugium, have fun setting it up!

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