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Building the base
One of the big decisions any reef keeper has to make is choosing the substrate. My other reef tank started out Berlin (no substrate, good skimmer) and I ran it that way for about 8 years. It was perfect. I never had any problems keeping anything, everything thrived, I never had detectable nitrates or phosphates, and obviously never had an algae problem of any kind. What a joy it was! When the live sand and plenum rage was in full swing, I caved in to my tendency to tinker, and I added a sand bed and plenum to my tank. Things were great for about a year, but then I found myself continually battling algae, despite taking every obvious step to eliminate the problem. While nitrates and phosphates were never once measurable with LaMotte kits, there was obviously a lot of nutrients in the system, which were quickly and efficiently bound up in the algae, thus never registering on the test kits. To make a long story short, I came to realize that while the sand looked good, it had made keeping the reef healthy and algae-free much more difficult than it was before. This led me to the conclusion that I didn't want a sand bed, at least not in the main tank. Secondly, I learned that the sand made the tank look so much better that people often commented about it. So, I want the look of a sand bed, without the problems I experienced before. Hmmm.... How can I do that? One day while reading about Aragocrete on the GARF site it suddenly came to me - I could make an Aragocrete bed in my tank - no worry about crud accumulating in the sand, but without the look of a bare-bottom tank! Also, I learned from my previous tank that I hate power heads. They are ugly. If you hide them behind rocks, they will fail, forcing you to tear apart the reef to clean or replace them. They can leak current into the tank so badly I can feel it (My fingertips are very sensitive for some reason), and they have ugly power cords. They also add a great deal of heat into your water. Yuck! Worst of all, I once came home from a week vacation to find my GFCI tripped and my tank water cold and gray colored, as if full of carbon fines. After looking at all the equipment, which seemed to be fine, I reset the GFCI, thinking maybe my carbon bag had somehow gotten stirred up. Pumps all kicked back on - looking in my sump, I saw the flashing light of an electrical arc of some kind, UNDER THE WATER. My Rio 2500 (six months old) had cracked and was really screwed. I lost hundreds of dollars worth of coral. You can read more about my pump setup in the Equipment section, but the relevant point here is that I was going to have only external pumps and thus some PVC pipes in the tank to channel the flow. I sketched how I wanted my reef to be shaped, including some larger arches and such, then I planned how the PVC pipes would go to help build the structure. So, first I plumbed all the pipes, then I poured an Aragocrete base in the
tank, covering much of the pipes. The Aragocrete is highest directly under where
the rocks stack, and tapers out to zero depth at the front of the tank, where I
planned to put a thin sand layer which I can easily vacuum and replace whenever
I want. This helps ensure that detritus doesn't accumulate under the rocks. The
PVC pipes make towers with several "nozzles", which I simply had to
hide/cover with rock, ensuring the water will flow properly and not be
obstructed, while hiding the pipes. To the right you see the first part of the internal plumbing. Where the pipes go up is where I would eventually have the reef structure rise up. Note the different heights. At this point, its hard to believe it will ever look good. People who came by and saw the tank at this point looked at me as if I was crazy!
Here I am putting in the Aragocrete base, which I made from white riverside cement, oyster shells (from a farm supply store), and on the top layer CaribSea Reef Sand (for the nice look). At this point, it was still pretty hard for people to believe that it would ever look good. The black nozzles are just 1/2 inch adapters for flexible sprinkler pipe, available at any Home Depot. None of the PVC pipe is glued, because I don't care if it leaks a tiny bit (its under water anyway!) and that way I can move and adjust where the black nozzles point to accommodate the rock structure later, ensuring I don't block the flow with rock while trying to hide it. Couple of construction notes here:
Once all the base was in, it looked a lot better, though still its hard for
most people to have the vision of what I was doing. Still most people would come
through and stare at the pipes and look at me like I was crazy. After about 3 weeks the pH was pretty stable, so I drained the tank, rinsed it out really well, and filled it up with RO/DI water, and then added the salt mix. Since nothing alive was in the tank yet, mixing the salt in the tank itself was the easiest. Switching to salt water somehow made the Aragocrete decide to release more CaOH and drive the pH up again. I planned on this though, since others had the same experience and shared it on the net, so I let it cure another week in salt water while I was installing the pumps, skimmer, heaters, and other equipment. Still didn't install the lights, since they would be kind of in the way when adding rock. I planned to do the lights after adding the rock.
Its alive!Finally - adding some life to the reef! I ordered 700 pounds of live rock in two separate shipments. I knew I wouldn't be able to aquascape the whole reef in a day, and I also knew if all the rock was in the tank, there would be no room to work. If the rock was NOT in the tank, it would be rotting and dying on the floor. So, I ordered 400 pounds the first time, then another 300 pounds several days later. I put the 400 pounds on one side of the tank, then built the reef structure on the other side. Doing the last third of the tank was the hardest, since I had little room to work with, but I managed. It took me about 2 solid days (10 hour days) to get the structure how I wanted it for the first 400 pounds, and another 12 hours for the second shipment. Whew!
Basically, the idea is that you get a power drill, a very long drill bit, and a bunch of acrylic rods the same thickness as the drill bit. You drill holes down through the live rock and insert the rods into the holes. In my case, I would play around with the rock structure until I decided how I wanted to stack it, then take all the rocks in the stack out onto the floor, remove the top-most rock, and drill down through all of the rest of them at once (but put it on something so you don't hit the floor!), and stick the acrylic rod all the way down to the floor. I would leave the rod sticking a few inches out of the top of the stack, then drill the underside of the top rock and finally put it in place. This works like a charm. I've never had any problem with shifting rock, and the acrylic rods are invisible (mostly inside the live rock!). Any rods that were left sticking out I simply broke off at the rock, and the coralline covered it.
Here's a close up of the first rock tower, from the left side. The white PVC is nowhere to be seen, and the stack is perfectly stable. I tested this by grabbing the stack and trying to move it back and forth. It shifts/bends slightly as the rods bend, but springs right back. Once I had half the tank done, the skeptics started to believe! Some people even would come by and ask if I had taken the PVC pipes out! Below are some pictures of the final structural result. The white pipes are completely gone, and the structure is quite complex, but perfectly stable. Unfortunately, I can't find any pictures of the finished structure with just the rock. These pictures below came a few weeks later, and have coral and fish already added. The angle of these pictures makes it difficult to see the arches and complex structure, but if you look for it, you can see them.
The The picture below on the right shows the left side of the tank, from the front view. On the extreme right you see an arch which is in the middle, leaving the space open at the back of the tank. On the extreme left is the same arch you see in the picture above, just viewed from another angle. Nowhere do you see the pipes, and it is perfectly stable! After a few months the PVC is covered with coralline algae, so it is nearly impossible to notice the pipes, even when you look for them!
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Another thing I learned
from my previous tank was that it is really hard to get the rock to stack
properly and stay put. I knew I wanted some cool structure, with arches and
towers - not just a wall. But snails, urchins, and mysterious monsters are
always knocking things over. To handle this I planned to do two things. First, I
would attach the rock to the PVC pipe towers with inconspicuous cable ties wherever possible for structural
stability. Secondly, I would use the ingenious idea from Nilson and Fossä of
using acrylic rods to hold the rock. This works brilliantly, and I thank these
guys for sharing this idea in their great book, 
Here you see the first
PVC tower (far left of the tank) is effectively covered. The flow from the
hidden pipes is not blocked, but the pipe is virtually invisible. Some of the
nozzles actually stick through holes in the rock to help hide them. This first
stack took about 2 hours! I was feeling overwhelmed with the task left before me - but
the rest went faster. In all, it took a few days of work to build the reef
structure. I was left wishing I had done a tank half this size! This first tower is eventually one side of a big arch.
picture on the left
is the same view as just above. The rock stack on the right has been joined via
an arch with a stack on the left, against the back of the tank which hides the
PVC pipe return (still visible above). 