Well, I decided to go a unique route for my background. Real rock. I hit up the garden center today, and I had all this rock to choose from, but I was targeting one specific type.
This was just a wee bit of what they carry:




I really wanted this piece, but it wasn't the rock I wanted:


This is what I wanted, black feather rock. About the same weight and texture as lava rock:


I added in the gallon jug for reference:


So basically, it will have a black "lava rock" background. Yes, a water fall is eminent, and it will be planted with ferns, violets (both standard and mini), a few mini gesneriads, and a butt load of aquatics in the aquatic portion.