Jake: I love reefs, I love corals, and I love everything that lives with them and around them. But when it comes to marine aquariums, the keeping, growing and understanding of corals is closest to my heart. To that end I have refined my own reef keeping technique to focus as much on corals as possible, in order to provide them with the best growing conditions, which doesn’t include a refugium. Not only do I not use refugiums, I don’t really keep reef tanks, I keep Coral Aquariums. Once upon a time when we didn’t know what were doing when it came to keeping marine animals in a glass box, it made sense to try to recreate the complete ecosystem in order to keep anything alive. Now that we know much better what different types of marine animals need, we can fine tune their individual needs and I feel very strongly that refugiums are not a part of that equation. On paper, the theory of having a refugium with its associated micro- and macroalgaes, supposed denitrification and variety of ‘pods can supposedly help to keep a successful aquarium. But in practice, for the vast majority of marine aquariums, I don’t believe you can point to a system and say that its success hinges on the inclusion of a refugium. If you really like refugiums, and all the neat stuff that grows inside, you’d be better off setting one up next to the main display and pretending that it’s plumbed into your main coral or reef aquarium. Julian: What I really dig is pods and sand. If I could put a mountain of sand in a tank I could call it a day and be happy watching the worms dig burrows next to the glass. To me the whole coral and reef fish thing is just a food source for my precious worms, pods, and sandbed. Algae, seagrass and mangroves just tie it all together like a pretty little bow on top. OK OK, so I exaggerate. Truth is, I love corals and all sorts of marinelife too. I think that coral-only aquariums are just fine, and feel the same way about fish-only tanks. I don’t fool myself in the fantasy that a reef aquarium is a perfect replication of the natural reef but I do like incorporating diversity and different habitats within the same circulating system because there are numerous benefits. Set up a tank next to your display and pretend it is connected? That would mean a separate pump and auto top off system, not to mention other ancillary filtration devices. Seems better to me to pool the resources and reap the benefits. Vargas Spouse factor: A refugium is, let’s face it, another aquarium, but you get a pass on it because it is connected to the display tank as a "filter". Is a refugium necessary? Of course not, just the same as it is not necessary to utilize a protein skimmer, or a calcium reactor. A refugium is just one among many water management devices that one may choose to utilize, with benefits that go beyond water quality management. I really like the direction Jake is going with focusing on the corals’ needs in a display system (or even a culture system). We’ve progressed this far but there is still much to be learned from that. Depending on the scale and the desire to incorporate a substantial fish population one must choose a technology solution or use refugium "biology". One may combine them too of course. It is a question of what is easiest to maintain long term.