It can seem endless waiting for the aquarium to ‘happen.’ All the equipment to research and obtain never mind the mounting cost that always seems to be more than estimated. Nevertheless, the aquarist knows when the really exciting time is close as thoughts of aquarium interior design arise.
It may be a fish only system that is being considered, or a full-blown captive reef. Whatever, there are some considerations that must be applied, and other aspects can be the aquarist’s free hand.
The aquarist needs to decide, or maybe already has, what type of rock is to be used. Is it going to be live rock, or will it be porous and inert rock? Whichever, the aquarist needs to ensure that there is sufficient rock to complete the structure in mind. In addition, if live rock is to be used then there must be sufficient of high enough quality to ensure the filtration of the aquarium will be adequate.
Seawater flow in the aquarium is very important. Good movement ensures that there is good gas exchange at air/water interfaces. Flow throughout the rock formation is important as oxygenated seawater is available everywhere and the chance of stagnant areas is minimised. It also means, in the case of live rock, that the beneficial bacteria can inhabit more rock areas thus increasing available filtration (subject to available nutrients). So the first item to be kept in mind is that the rocks should not be tightly packed but more of a loose formation, though of course they need to be stable. Naturally obtained rocks are usually very random in shape and this is of help – it would be difficult to pack them closely together.
Another point to be kept in mind is that livestock need a home where they can feel secure. For example, fish need somewhere to retire for the night. It is a good idea to try and build in a cave or two as construction proceeds. As already said, it is likely that the rocks themselves, being randomly shaped, will create crevices and channels.
It is great fun creating a rock formation or reef. Of course, the aquarist with a nano aquarium will have less scope than someone with a much larger one. The small aquarium may take very few pieces of rock, but it can be surprising just how many formation variations can be tried with those few rocks. The larger aquarium can have a formation much more like a reef (whether a captive reef is intended or not), and the very large aquarium provides the freedom to really be creative.
Quite a few aquarists create a reef which is well constructed and interesting. These reefs go from one side of the aquarium to the other, and their top and front surfaces are generally straight. There’s nothing wrong with that, and if the aquarist wants that kind of construction then fine, so be it. However, these reef types have been likened to a greengrocer’s shop with the vegetables (corals) laid out. If the aquarium is fairly large, that is not a nano, why not slope the reef from one side to another, or run it flat and then let it drop away before it gets to the other end? In a large enough aquarium, the formation could start high, drop down lower in the middle then climb up again at the other end. The centre could pull back from the front glass to give some swimming space. In a larger aquarium, a central but offset pinnacle could be used, with a decorative sand bed around it. Or there could be two pinnacles, again with decorative sand around the bottom. As said, it depends on the size of the aquarium, but there is scope for imagination whatever the size might be.
The aquarist is going to look at his/her creation a lot in the future, so time spent in the initial construction of the reef is time well spent. Anyway, as said, its fun!