The reason I like this type of background is that:
a) It doesn't take up a lot of space like other backgrounds
b) It provides a series of caves
c) I think it looks good
d) It's modular and can fit to any scenario
e) It hides the intakes for filters, CO2 diffusers, heaters, etc in the compartments behind the wall.
Using black bristol board, I cut a piece to go on the end as a black background. With the holes in the rock wall, you can still see through it a little bit so this will eliminate that.
To secure the rocks, I used Clear GE Silicone II. Silicone I will peel from the PVC gutter. I used "Windows and Doors", the one without any mold inhibitor or "BIOSEAL" as they call it.
I collected the limestone from construction sites around town, but you can use any kind of rock that you want. I will be using large limestone pieces for the hardscape, so I wanted to blend.
First, I rinsed the stones in some water for a few minutes, then I let them dry.
Next, I applied the silicone and started laying down the rocks one by one so that each was seated securely in the silicone and no large gaps between the rocks occurred. I started with the tops for no real reason.
Then I did the next section.
Here they are.
Then I started to do the sides.
And finally this is the finished product. The bottom is not completely covered as it will be under sand. I had to use very thin rocks on the sides as clearance between the wall and the glass is minimal (different aquariums will have different side allowances for this).
Time to dry, and then fill up the tank and get it going. Should be by tomorrow.