Oooo...I envy you that magnificent pile of rose quartz!
Here is what I would do..first a background to hide the cords. This will put all attention on the tank, not what is behind. I would go with black. (You can paint the outside of the back with several thin coats of latex paint, allow lots of drying time between coats.)
Then break up the pile into 2 piles, a large and a small. Both piles off center...maybe put the bigger pile in the back right corner, and the smaller nearer the middle and front. Just do the bubble wands under the biggest pile. Consider gluing the rose quartz chunks into some other shape than just a pile....maybe a series of cliffs and ledges? That will give some height and draw the eye up. You can use clear aquarium sealant to glue them together. Just make sure you come up with a design that is pretty much stable by itself, and use the glue as a stabilizer. You do not want any thing to come loose and drop! You might even consider putting a sheet of egg crate diffuser down first, then put the black gravel on top of that, then put the rock formations. That way, if a piece does fall, the "hit" will be spread out over a larger area and less likely to break the bottom glass. You can paint the egg crate flat black with Krylon Fusion, and you will never see it under the gravel.
Then a row of dark green plants along the back, bunched up little, not in a straight line. Maybe put a few smaller versions of the same plant coming out of the piles of quartz.
I will accept payment for my decorating advice in the form of a chunk of rose quartz...thank you very much!
