TheReef.info 

Between 2000 and 2004 I ran a fairly traditional 530 litre reef aquarium with a small under-tank sump, maintaining a broad collection of LPS and soft corals.  In the aquarium was a Deep Sand Bed (DSB) held above a plenum, and a wall of live rock running along the back.  It seemed to be successful but by 2004 I was intent on upgrading so I could keep more demanding SPS corals, and this was the excuse for me to fundamentally rethink my setup and objectives. 

I determined that my ultimate goal would be a large, SPS dominated, aquarium but I also realised that I needed to walk before I could run.  So I decided that I would first upgrade my existing aquarium and run that as an SPS system for a couple of years.  In purchasing equipment for this interim step I kept in mind my end goal, and that was why some of the equipment used in the system was so oversized. 

As part of that upgrade I changed over from the small sump under the aquarium to a more systemised system, with a large 750 litre sump in the adjoining garage feeding both the main aquarium plus some smaller ones located in the garage.  All the old live rock and the DSB and plenum were ripped out, with the old rock cleaned and placed in a cryptic (i.e. unlit) zone in the new sump.  You will find more details on the filtration and other equipment in the Set-up section.

A biotope aquarium

If you look at many hobbyist SPS aquariums you will find they often contain large numbers of different species of fish and corals, from all corners of the globe, and from very different parts of the natural reef, living unnaturally cheek by jowl in a blaze of different colours.  And it is hard to resist the urge when visiting a shop for 'just one more' coral or 'one more' fish without considering where it actually came from.  But we risk ending up with an unconnected polka-dot collection of fish and corals, making for very unnatural reefs.  Of course such setups can still be very beautiful and successful aquariums, but I wanted to adopt a different approach for my new reef.  I decided to try and have some kind of theme to my aquarium and opted to try and set-up a biotope aquarium, modelled on a specific section of a coral reef.

biotope (plural biotopes) n

I had been inspired by the book Reef Secrets by Alf Nilson and Svenn Fosså, which describes the challenges and satisfaction that can come from trying to recreate a specific ecological niche in a marine reef aquarium.  I reasoned that having some underlying rationale to the stocking would also reduce the scope for succumbing to expensive temptations when visiting my local stores.  And I was attracted to the idea of having fewer species of fish and coral in the aquarium, but more heavily represented, which I thought could create a stronger visual impact.  

Hawaiian bench zone

Having already reduced the stocking options available to me by going down the biotope route I then cut them even more severely by deciding the biotope would be a Hawaiian reef.  I admit I simply did not appreciate just how much of a difference that one decision would make when I started out.

Due to the geographic isolation of the Hawaiian Islands they are much less diverse than other reefs, especially those in the neighbouring Indo-Pacific.  For example, in Hawaii it has been stated that there are just 52 species^* of stony corals; whereas in the western Pacific island of Palua there are over 300.  However, the corals that are found in Hawaii tend to be less specialized and therefore distributed more widely about its reefs, although a relatively few species still tend to dominate.  Finding a sufficient number of indigenous Hawaiian coral species in the UK to populate the aquarium has therefore been particularly difficult. 

So why on earth did I choose Hawaii then?  Blame the Black Surgeonfish (Ctenochaetus hawaiiensis) also known as the Chevron Tang after it's juvenile patterning.  I had purchased this fish over a year before and soon found he was a real character, and was consequently loath to loose him.  He was also a good example of some of the many compensations Hawaii does offer - its isolation allowing species to develop and thrive that are unique to Hawaii, or else rarely found elsewhere.

The abundance and distribution of coral in Hawaii varies according to the distance and depth from shore.  The primary cause for this zonation is the effect of wave exposure, although changing salinity, sedimentation, and temperature levels can also be important.  Guides to the reefs of Hawaii tend to divide the reef into four main zones: reef flat (0-2m); reef bench (2-10m); reef slope (10-30m); and rubble zone (30-40m).  Juvenile Black Surgeonfish are found in areas with lots of coral from 20-30m in depth, but the adults are found in shallower waters.  I therefore decided to model my biotope on the edge of the reef bench/slope zones, around the 10m mark, as this seemed more appropriate for the adult, plus it seemed to be the area that would offer me scope for the greatest variety of coral types.

You will find a lot more detail on Hawaiian reef structure and ecology, the corals and fish found there, and how this has all been influenced by the geological structure and isolation of Hawaii in the About Hawaii section of this site.

Looking forward

Opting for a Hawaiian biotope created some significant challenges and led me to adopt a different approach to the aquascaping (see the description in the Aquarium Set-up section).   As the system matured I think that aquascaping style turned out to be at least as visually pleasing as more traditional approaches.  Meanwhile I found the biotope discipline not too constraining, but intellectually stimulating and the satisfaction of hunting down appropriate species rewarding.  I therefore intend to replicate that style, and the Hawaiian biotope theme in the next upgrade to a 2,300 litre (600 US gallon) main display.

* This figure of 52 stony corals is frequently quoted in literature on Hawaii but a skim through Veron's Corals of the World suggests the presence of more than 70

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