- Refugium (fishkeeping), an appendage to a marine, brackish, or freshwater fish tank that shares the same water supply.?
- a region that has remained unaltered by a climatic change affecting surrounding regions and that therefore forms a haven for relict fauna and flora
Above are a few of the definitions that you will find if you research the word refugium. Although accurate, these definitions only touch the surface of what a saltwater refugium actually is, and what it can do for your saltwater aquarium. Hobbyists often take the plunge into refugiums for a few basic reasons:
The main reason and benefit to adding a refugium to an aquarium is to help keep nutrient levels in check. A refugium with the proper setup and macro algaes can aid in reducing the rate at which nitrate and phosphate are added to the aquarium. The fuge is able to do this through what we aquariests like to call “Biological Filtration” – where actual living things are able to take up the excess nutrient via biological processes. One of the most known process is photosynthesis, where the macro algaes in the fuge use the harmful excess nutrient as food to grow, helping to keep our aquarium water cleaner and habitable for longer periods of time.
A refugium can also benefit your aquarium by providing a safe haven for certain fish or inverts, as well as a safe place for live food to grow. Marine Copepods (pods for short) are a very small crustacean that many fish can use for food. Given the right conditions (aka a refugium), copepods can multiply very quickly, which can help supplement feeding your fish and corals. The refugium can also be used to house fish or inverts that have been messing with expensive corals, or vice versa, as a safe place for fish or inverts who are being bullied by other fish and inverts in the main aquarium.
1. An extra aquarium, or a store bought dedicated refugium.
To set up a refugium, you will need a seperate tank, or a store bought refugium. In my own experience, I have built my own and bought serveral different types of refugiums. I would reccomend building your own as you can tailor it to your specific aquarium, and it is always fun to take on a new DIY project. Not much skill is needed to do this, and you can look at pictures of other peoples refugiums on message boards, such as reef central, to get an idea of how to set it up correctly. Common reccomendation is that the refugium should be at least 1/10th the size of the main aquarium
If you choose to buy a seperate refugium, be prepared to spend about $150+ depending on the size of your aquarium. Store bought versions of this filtration come in 3 different types:
2. Deep sand bed
A deep sand bed in a refugium is a crucial thing to have. First, they provide a place for processing and exporting some dissolved nutrients. Second, they provide a place to recycle detritus, excess foods, animal feces and other particulate material into useable forms. Finally, they provide a food source for many animals. Deep sand beds, or DSBs, can be set up with sand or mud. I reccomend the following:
3. Macro Algaes
Macro algaes are one of the main ingredients to your refugium concoction. There are many types of Algaes, some more efficient at taking nutrients than others, but they all pretty much do the same thing. Personally I would stay away from culpera, as it has been reported in the past to have spread to the main aquarium. The safest and most common macro algae to use is Chaeto. I would reccomend trying to buy or trade for this locally as it is common and cheap.
Lighting in the aquarium hobby, especially the reef keeping part of it, is a very important thing. This is no different for refugiums. You must have the right amount of light as well as the right spectrum of light for your refugium to be successful. The easiest thing to do for this portion of the refugium would be to go to your local hardware store, get a 100-150 watt equivalent flood light in the 5000-7500k light spectrum, a cheap reflector, and set that up right above the refugium. You may need to add more light depending on the size of your fuge. Should you want a more presentable and official looking fuge light, you can go with one of the many available T-5 or power compact fixtres, or even an LED fixture. Just make sure that the bulb specturm is in the 5,000-7500k range as this is the best for plant growth.
Light schedule is another common question when it comes to refugiums. In my own experience I have used both a light schedule and light on the fuge full time. The difference between these is undetectable (in my opinion). The most important thing to remember about the refugium light schedule is that the light should be on when the main aquarium lights are off. This is reduce the competition the macro algae has to grow as well as keep your pH from fluctuating.
Flow through the aquarium should be very slow. You want the water going through the fuge to have ample time to be filtered by the biological filter. Also, many macros grow more efficiently in slower moving water.
Here are a few examples of what an established refugium looks like.