Aquarium refugiumsby Mick As the name suggest a refugium is basically a refuge for macro algae, copepods, amphipods, shrimps & fish species that require quiet surroundings away from predation, bullying etc.
They are normally connected to the main display tank or in close vicinity as they need to benefit from the high water quality that is maintained in a reef tank. And this can only be achieved by the water being pumped directly into them which is then allowed to drain back at a steady, constant pace. Some fish keepers keep refugiums purposely to breed their shrimps & copepods. They also provide ideal conditions for seahorses, mandarins, pipefish & all fish that require calmer water flow.
SETTING UP A REFUGIUM:
Any small tank can be used to create a refugium; in fact on the market nowadays it is possible to purchase a hang on variety which is just as suitable.I have used a 10 gallon tank for this purpose in the past.
Now we need to supply a water supply to fill the tank. This is done by means of a small water pump or even better a direct feed from the protein skimmer as the oxygen content will be at it’s highest. Placement of the feed pump if used should be below the water line in the main tank so that oils, proteins etc. are not pulled through from the water surface, & ideally the outlet should be fed back to a sump by means of pipe work & let gravity do the work – if not then a small return pump would be required to feed back into the main tank.
When I have set mine up I always used a sand bed with a 2” depth with a small amount of live rock rubble as once this is established it can also aid removing nitrates from the water & found it a good place for caluerpa which will also consume nitrates & phosphates, various other macro algae which would otherwise be food for the tangs in the main tank therefore defeating the object of keeping it on display.
These are also an excellent place for keeping a thriving copepod population which can be harvested for feeding your livestock. Once your caleurpa has settled in & growing well it too can be harvested to feed your herbivorous fish.
LIGHTING YOUR REFUGIUM:
Every refugium should have its own lighting source & I have had good success with the clip on halide lights, no need for a large wattage I found 40-50 plenty, sustaining my caleurpa growth with no problems, but people I have spoken to have as much success with a small T8 or T5 lighting system .
There are no set rules for the position of the refugium, be it at the side of the tank, directly above or even hanging on the side – as long as the water feed is constant from your main tank it will be a great addition & also aid in the filtration of your system.