A Refugium is an appendage to an aquarium which can be used for a variety of purposes, such as denitrification and nutrient export, as well as creating a sanctuary for beneficial micro-fauna to thrive and multiply. In a pinch it can also be used for isolating antagonized or antagonistic tank inhabitants. Refugiums come in many forms and sizes, but the vast majority of them have a distinctly rectangular shape. So I took it upon myself to build a cheap and simple corner pentagon shaped refugium.

You might ask, why a corner refugium? And for that the answer comes in two parts.

1.) In my case, my Nano Reef, a Flat Hexagon shaped tank, stood on a very old corner table that I have had since my childhood, which for sentimental reasons I was not very eager to start drilling holes in for the plumbing. This meant that any Refugium had to be located behind the display tank.

2.) Space is everything, and behind my display tank there wasn’t much space for a standard rectangular shaped refugium. I had already, for about a year, been using a makeshift refugium made out of a couple of small plastic aquariums, which was proving to be inadequate for the task, having too little surface area for the macro-algae that I was using for nutrient export, to flourish. And then it suddenly hit me… who ever said that a refugium “must” be rectangular in shape? I realized that If I used a triangular shape I would be able to make much more efficient use of the space that existed behind my display tank, and in so doing having a refugium of far greater volume than I would ever be able to have with a straight up rectangular shape.

Now with the question of “why” answered, let us continue with “how”.

Now I suppose one could have taken and just built a perfect triangle shaped aquarium from scratch, which would definitely have been the most “efficient” in sheer surface area. But aside from the matters of practicality and the maintenance in such a shape, at the time I simply did not possess experience, materials or the time required for such a major project. So instead I opted for simply purchasing a complete 50 liter Corner Pentagon shaped aquarium and use it as the base for my new refugium. This later proved to be a good decision when the time came to install the equipment. So at my disposal I now I had:

– A 50 liter Corner Pentagon Aquarium
– A Tube of Silicone Aquarium Sealant for a Caulking Gun
– An unused cover glass from another aquarium

First I had the cover glass cut into a pair of baffles that were 20 and 21 centimeters tall respectively, which would allow for the water to flow through the refugium while maintaining a constant water level in the main chamber. After that came the real tricky part, getting the baffles in place and getting into the cramped confines of the corners of the aquarium with the caulking gun. As this was the first time I had actually done anything like this it wasn’t very pretty but I did manage to get good seals on both baffles.

With the baffles in place and the sealant dry, it was now time to put the refugium away to cure. A week later it had finished and all the odors were gone and it was now time to test to make sure the seals were strong enough to hold water properly.

Confident that the seals were strong after the freshwater tests, all that was left to do was to remove the old makeshift refugium and set up the new one. Once in place equipment such as the overflow box, return pump, protein skimmer, heater and an Automatic Top-Off system were installed, followed by the addition of sand, live rock and a clump of Chaetomorpha macro-algae which would be used to export nutrients from the system.

In hindsight I feel that the return chamber on this build is a bit under dimensioned, necessitating the use of an Automatic Top-Off System to keep the water level from dropping to fast from evaporation, as well as not allowing for additional equipment such as the skimmer to be installed there. But overall I’m quite happy with this build, and as for its effectiveness I do believe that the monthly Cheatomorpha harvests speak for themselves.

And that… is how you go about “building a corner refugium”.