I have a bad habit of looking at driftwood whenever I'm anywhere that has it, and in the planning stages of my new 40B tank I picked up a couple pieces of cool looking mopani. I have never included rocks in an aquascape besides the various pebbles in my 60 gallon, but I really want to. What kind of rocks might look best with mopani wood? Also, would anyone have advise on a good substrate to use? Pool filter sand has done me wonders in the past, but I considered maybe mixing it with tan colored flourite?? Would mixing it defeat the purpose of the flourite? Should I try using black flourite, or would that look odd with the lighter colored mopani wood and rocks? I want as natural of a look as possible.