Building an Effective Refugium

If you don’t already have a refugium attached your aquarium, you’re missing out big time. Refugiums are perhaps one of the single best additions you can make to your set-up. If saving time and having a stunning reef is your thing, get hooked up with a refugium. Immediately.


What’s so Special about Refugiums?

What makes refugiums such a great addition? It all ties back to creating your reef around natural cycles and processes, and that’s exactly what a ‘fuge does. Refugiums are basically a diminutive external tank that you hook up to your big-sized tank.

A refugium is typically filled with all sorts of natural goodies, from live rock, mud or sand, and algae to a whole host of micro-organisms. When filled with the right types of creatures, like Copepods and micro-algae, it can, on its own, become a completely self-sustaining habitat.

The real magic happens when you hook it up to a fully functioning reef aquarium. When the two come together, nature happens. The water, via a pump, is exchanged between the two. Copepods and other fish-feeding organisms go into the big tank, and algae and detritus go into the other.

The fish are happy because they get a fresh supply of nutritious food, and the micro-organisms in the ‘fuge are happy because they were just presented with tons of tasty detritus tidbits. It’s a win-win for all parties involved.

On top of that, refugiums mimic the natural rhythms of reefs of the ocean. The natural flow of water between the two ecosystems and the exchange of organisms recreates the natural filtering and water balancing systems of the ocean. Refugiums are excellent for keeping the water clean, oxygenated, and pH balanced, especially at night.

If you want, your refugium can even double as a culturing tank/quarantine tank. It’s a great place for copepods to grow and reproduce, without fear of predation. If you have ever had problems with over-poached pod colonies, a refugium could be a great solution.

If you have sensitive fish, like Mandarin Gobies, a refugium is a great place to get your them acclimated to your aquarium. It gives them a place to eat plenty of food and relax without competition from other fish. A week or so in the ‘fuge should be long enough, and then you can put them in the main tank.


How to set up a Successful Refugium

There are so many different ways to set up and stock a refugium. It’s not as if there’s one “right” way. You simply have to decide what’s best for you.

That being said, there are some specific guidelines that every aquarist should follow when setting up a refugium. For example, they should be stocked with rich mud or sand and a big hunk of live rock. Correctly stocked, your refugium should just look like a smaller version of a reef, with everything downsized. After all, you still need places for your organisms to thrive and feel at home.

Less ideally, you could have multiple small hunks of live rock, for a similar, but not quite the same effect. The mud and sand layer should, depending on the ease of cleaning and type of algae you stock it with, be 2-4 inches deep, give or take depending on your situation.

Now, on to the fun part: Choosing your favorite filtering organisms. There are plenty of different combinations for you to use in your ‘fuge, but there’s a formula to keep in mind. In general, you’d like to have a mix of hardy, self reliant plants and excellent filter plants.

Examples of hardier plants include Mermaid’s Fan, Red Titan Algae, Sargassum, Fire Fern, and Flame Algae.

If you’re looking for the best filtering plants, choose options like Chaetomorpha(Chaeto), Spider Algae, Manatee Grass, Oar Grass, and Suction Cup Caulerpa

A good combination of the two types makes for a great mix of filtration, eye-candy, and sustainability.

When it comes to stocking your refugium with food for your fish, like copepods, there isn’t a lot of hassle involved. Start by choosing your favorite plankton. We recommend either Tisbe Pods or Tiger Pods. One bottle will be enough. Remember – they reproduce on their own. Next, pour them in the refugium and let them do their thing. That’s all there is to it.

Simply introducing a colony of pods should be enough, if your refugium is set up properly. The naturally occurring algae and detritus will be enough to feed them. However, we think you can do better.

If you’d like to up your copepods’ nutritional value even more, as well as safeguard against starvation and crashing, you should pop for an algae supplement, like Green Phyto. This gives your pods an added boost in micronutrients, as well as diversifies the whole colony. A couple of tablespoons of the stuff should be enough.

As for pumping the water between the two tanks, don’t get too carried away with the water flow. The goal of a refugium is to have a rich, fertile environment for organisms to thrive. If you want that whole process to move along smoothly, the flow between tanks must be gentle and slow. If the flow is too brash, you’ll have excess shifting of soil and quickly transferring detritus, making it harder for anything to really thrive. As a general rule, you should aim for an average water flow equal to your refugium per hour. For example, somewhere around 30 gallons of water per hour in a 30 gallon tank is a good bet.


Wrapping Up

Refugiums are an excellent addition to your aquarium set-up. Done right, they can be aesthetically-pleasing, massively-filtering, and even fun to put together. A good ‘fuge could potentially save you loads of time and headaches, all the while double as a culturing tank and a sustainable food source. Every aquarist should give it a shot at least once.

Jett Murdock
Jett Murdock
Jett Murdock is the resident reef writer here at When he isn’t writing about all things reef related, he freelances over at He's a seasoned writer with 3+ years of experience writing everything from product descriptions to essays.

3 thoughts on “Building an Effective Refugium

  1. Ovais says:

    When is the best time to start the refugium? At the beginning when setting up the tank or once the tank has cycled and stocked. Also, if the answer is in the beginning while the cycle is taking place, do you add everything into the refugium, like the algae and copepods, or start out with just LR and sand/mud.

  2. Tim Williamson says:

    Can coppode be grown in a 10gallon aquarium with rock an small pump to move water an air pump with ridge tubing an a6500k photosynthesis bulb

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