What are the fundamentals of a refugee?

A fuge is a filter that is alive. A refugium’s sole purpose is to dedicate a specific space for the growth and/or cultivation of algae or animals in a predator-free environment. A hang on back filter would be a very basic refuge. When changing the filter pads, keep an eye out for various worms, copepods, and amphipods. Because fish cannot reach them, these pods have discovered that they can live fearlessly in the filter pad. As a result, the basic refuge is born from a simple back-hanging filter and filter floss.

What are the advantages of a refugee camp?

A refugium is essentially a container that has been set aside for one purpose and one purpose only, as described in the previous section. Refugiums can be used to grow macro algae to feed hungry tangs or as a natural filtration system. Fuges can also be used to grow amphipods and copepods (pods). You can even use a refuge to keep other creatures that you can’t keep in your main tank, depending on your needs.

By utilising the concept of nutrient export with other more desirable macro algae colonies living within the fuge, refugiums can act as living filters to limit the growth of undesirable algae. They can also function as a farm, cultivating and growing pods as a natural food source for fish and invertebrates. On a reverse photoperiod, a properly sized refuge can also help balance your tank’s PH chemistry via macro algae. The refuge, like the addition of a sump, can increase the total water capacity of the system, making it more stable.

What size refugium should I build?

Your refugium can be any size you want, but Fenner and Calfo (Natural Marine Aquarium Volume I Reef Invertebrates) suggest that the larger the refugium, the greater the benefit. As a guideline for sizing a large and productive refugium, 20% of the size of the display tank is suggested. A 10 gallon refugium will be much better suited to a 55 gallon display tank than a 5 gallon refugium or even a refugium of even smaller size. This is due to the refuge’s capacity to hold a large number of people. The more algae the fuge can hold, or the more substrate area you’ll need to cultivate pods, the bigger it is. A refuge that is too small can be just as restrictive as having none at all.

I’m not sure what I can put in a refugium.

Growing macro algae for nutrient export, PH stabilisation, and as a food source for hungry tangs and angels is the most common use for a refugium. This is far from the only application for a refugium. Plankton or amphipods/copepods can also be cultivated in refuges. Refuges with DSBs can also be set up as the sole source of nitrate export. Let’s say you have an established aquarium with crushed coral substrate and don’t want to go to the trouble of removing the old substrate and replacing it. Adding a relatively large DSB refuge will allow for nitrate export. It is recommended that your DSB refugium be no less than 20% of the volume of your tank, but ideally the larger the better. The depth of a DSB refugium should also be between 4-6.

If you’re going to use the refuge as a nutrient export device, you’ll need to light it the same way you’d light your display tank. For photosynthesis, the macro algaes you want to grow require proper lighting. Ideally, your refuge should be lit on the opposite day/night cycle as your main tank. This means that your tank is lit while your refuge is dark, and vice versa. The goal is to maintain a consistent PH level within the tank by providing a continuous CO2/O2 exchange.

If you want pods to thrive, you’ll need to create an ideal living environment for them. This would be the first place where there would be no natural predators. Second, either a thin layer of sand or a bare bottom should be provided, as well as a nice mound/layer of rubble rock. This type of habitat will appeal to amphipods and copepods. When the pods are moving around at night, they should find their way back into the tank. It’s not even necessary to light a pod tank.

As you can see, the exact layout of your refuge will be determined by the items you intend to keep there. Consider what kind of task you want your refugium to perform before designing and sizing it.

What is the best way to incorporate a refugium into my setup?

Hobbyists commonly place their refugiums in one of two locations. You have the option of placing it above or below the tank. Some hobbyists will place their fumes above the tank to prevent pods from being chopped up by the return pump. I don’t believe this because the pods will have to pass through a pump at some point, either to enter or exit the refuge. Remember how a simple hang on back filter was a very basic refuge in my previous example? No one put those pods in that filter, where they found a home in the filter floss. As a result, they had to travel up the intake tube and through the intake impeller before landing in the filter floss.

If you build your refuge above the tank, you’ll need to plum it so that it’s fed by a pump that comes from either your sump or your main tank, and then you’ll need to set up a gravity drain to return the water to the main tank. Never try to set up a dual pump system with one pump pumping water into the system and the other pump pumping water out. The problem with such a setup is that it will be nearly impossible to keep a duel pump system running for long periods of time with both pumps moving the same volume of water.

If you put your refuge below the tank, you’ll need to set up either a gravity feed from the display tank into the refuge and then a pump back to the main tank, or you’ll need to set up a secondary circulation system feeding out of the sump and back into the sump or back into the display aquarium.

I’m not sure how much flow I should put through my refugium.

The flow rate that will best suit your refuge will be determined by how your refuge is set up. If you’re using it for nutrient export, aim for a five-times-your-tank-volume-per-hour turnover rate. You can increase this flow rate to ten times your tank capacity if you’re using your refuge as a pod farm. If the refuge is to be used as a plankton farm, the flow rate should be much lower than even five times the turnover rate.

In conclusion, keep in mind that you are not limited in what you can do with your refugium, and you can even run multiple refugias on the same system. While the flow rate does not have to be equal to the flow rate within your tank, it also does not have to be so low that the refuge is classified as a stagnant body of water. Please use our forums to ask any questions you have about this article or about refugiums in general.