Once the aquascape has been perfected with nooks, crannies, tunnels, overhangs and interesting structures, it is possible that all your hard work can come crashing down. It may be a slow collapse, or it might just tumble down at once. Corals can gain so much mass to topple the rockwork that was balanced and stacked so nicely for so long. Some fish are known sifters, taking big mouthfuls and distributing them elsewhere. Cucumbers live to process sand, and in doing so undermine the rock causing shifting. And then of course, there is you: something needs to be changed, you decide to move one rock that isn't of much use and suddenly you wished you had three or more hands to hold onto stuff as you attempt to put that rock back where it was. It NEVER goes back where it was, ever. You thought you could simply pull it out, kill an offending pest anemone and put it back? Yeah right. Not gonna happen.
When I initially planned the 400g's aquascaping, I knew I wanted to create an underground acrylic foundation. However, I was cramped for space and decided to put all the sand in the tank to get it out of the way of my work area. The acrylic support structure wouldn't settle down to the bottom of the tank because the sand was in the way, and a lot of wasted time ensued. But I'm getting ahead of myself. Let me get back on topic.
Taking large pieces of 3/8" acrylic, I created three pads that would support the live rock. I also purchased 1/2" and 3/4" acrylic rod. With the deep sand bed 4" deep, each rod (or post) was cut at the minimum 4" tall. Some were taller, intentionally. The weight of the rockwork is distributed across many posts and no-one spot encounters a major pressure point.
Arranging how I wanted the aquascape to stand on each pad, I marked the acrylic with a Sharpie to outline where the rocks sat, arranged perfectly. The next step was to look at how the rock was be supported. Each rock needed two solid feet (3/4" rod) and then a taller post (1/2" rod) would be placed where it slide up into a socket. If the rock lacked any useful pocket, I drilled it to create a receiving hole. The rock would stand on two footers and the taller rod would keep it locked in place. The tripod system was created for all the base rocks, the ones that would be sitting on the pad.
The acrylic sheet was marked with an "O" for a 3/4" pillar and an "X" for a 1/2" post. All the pillars were the exact same height, and the posts were cut to the proper length to lock the stone in the optimum position. All the holes were drilled in the acrylic sheet, the matching post or pillar inserted and bonded with Weld-on #16. This was left to cure for an hour. Each rock was jigsaw puzzled into place as pre-planned, and the pad was ready to go in the tank. This process was repeated for each of the three pads. It's slow going, but you only have to do this once.
For any rock that would interlock the main base pieces, these were secured with the concrete mixture that Marco Rocks sells. It's a very simple system. Add a scoop of the powdered mix into a small bucket, add some of the liquid provided with the kit, and mix it well until it looks like pudding. If it is too dry, add more liquid. If it is too wet, add more powder. It won't take long to find the right ratio.
Concrete visible above. I was able to blend it in with rock rubble in the next two images.
I'd advise you only mix a little bit at a time because it sets up quickly... as in mere minutes. That's enough time to apply some of the concrete to the various spots, making sure to press it in and shape it so it adheres to both rocks equally. As soon as I had two or three spots bonded, I pressed some rock rubble sludge into the concrete to help mask it from sight. Move on to the next spot and mix up some more, bonding and blending until you're done. Use handy items to support any rock that doesn't stay in place: pieces of wood, balled up newspaper, styrofoam sheets & cups, etc. By the next day, the concrete is cured and water can be added to the tank.
If you want to fabricate some type of bridge or large shelf, grab some rock and bond it the same way. You could bond the entire aquascape into one solid structure, but my preference is to keep the bottom layer stable, allowing me to change the configuration (above that layer) based on how the reef is growing. Flow is another factor that can't be ignored. If the rock structure blocks the flow, it may need to be changed for better results.
Some choose to place the rockwork on the bottom of the tank and then add sand around it, essentially burying the rock entirely. I don't see any benefit from this. Some have even noted how smothered live rock turned sour and created a sulfur pocket in the sandbed. Additionally, rock on the bottom of the tank can still move laterally when sand is displaced, and the entire rock pile can begin to come down which may break some precious corals in the process. With the acrylic support system, all the rock is visible and functional, while completely invisible due to the sandbed. If a pump suddenly blows all the sandbed across the tank, the reef will still be standing where it should be. Alternatively, the glass may get scratched when the rocks fall toward the walls of the tank -- a real risk.
So let me get back to the sand war of 2011. My concern was that exposing live rock to air too long would cause cycling, and I wanted to avoid that at all costs. Cycling refers to the ammonia-nitrite-nitrate process that can take several weeks to complete. Instead, I wanted the rock placed in the tank and within a couple of days, the livestock. Water was added to the tank, high enough that it would keep the rock submerged. Surprisingly, I was unable to shift all the sand out of my way to place the first pad in the tank. My friend Wes was here to assist, and we tried all kinds of ways to work the pad down to the bottom of the tank, but it would not work. Eventually, I took off my shoes and socks, changed into some swim trunks, and started scooping all the wet sand out of the tank. At least 200 lbs of sand was removed. The rest was forced to one end, and finally a cleared area was ready to receive the rockwork pad. When all three were positioned where desired, the sand was then poured back into the tank. It was that night that I accidentally scratched the front panel of my beautiful brand new aquarium, and it literally broke my heart. I kept my arm between the glass and the bucket as I poured the sand out carefully, but the metal handle (where it hinges into the bucket) scored a horrific gouge in the glass in the process. Not some little nick. It was a big circular jagged squiggle in the glass. Besides marring the perfect glass pane, that is always where algae grows first and is difficult to erase because it is inside the scored spot. That was that, the damage was done, and I just had to live with it. How frustrating to do that on the very first day of the tank being set up though.
Now that I'm setting up the aquascape in the new 400g in 2013, I'm being very careful around the tank. I also didn't put the sand into the tank so the acrylic pads would go in quickly and easily. Last time, Wes helped me lower the pad with the rocks on it into the tank. This time, I placed the pad in the tank, then took each rock and positioned them as intended. Next I concreted the rocks together and let them cure overnight. All the used sand was rinsed out well, and carried in plastic bags into the tank. My blog on that process is here:
With the rock secured together on the acrylic pedestals, all the sand was added to fill in the void beneath. This worked great on the previous setup, and was designed to last for years. The only reason it came out prematurely is because the tank leaked forcing me to break down the system. This is the 400g 2.0 basically. It provides the opportunity to better document how it is set up, which I hope you find interesting and possibly worth emulating.
All the sand was smoothed out and saltwater was added to help level it out. I still have a little sand left, incase the tank needs a little more.
More water is next, plus a circulation pump and probably a small skimmer to help extract any organics since the rock has been exposed to air for several days now. There's no smell, fortunately.
Inevitably, people will ask me if that's all the rock I'm going to add. No, there is more rock that I'll be taking out of the 215g that you saw in the background of some of these pictures. That rock will be stacked on top of these foundation rocks. I'm excited to move forward on this project, and will continue to update Reef Addicts with the latest via my blog, as well as any article-worthy write ups.