I had a ssb (0.5") in my display tank which was just thick enough to cover my eggcrate I had laid down to put the rocks on. Bad mistake because the flow in the tank created sand storms and exposed many parts of the eggcrate. Eventually the sand became ugly and I contemplated for a long time but finally decided to suck out the sand exposing all the eggcrate. But I now have a new tank currently being set up, I have decided to go BB. But instead of smooth glass, I glued a thin layer of sand to the glass with Envirotex Lite which is a two part epoxy that is considered reef-safe. It dries hard as a rock and is rather rough to touch. Here's a pic of the faux pas sandbed around the drop cloth.
(please don't mind the mess and no the sand is not purple striped)
My plan is to have some seio's or tunzes aimed at the ground in the center to push out the detritus to the sides where I will be able to siphon them off. With a real sandbed, that will not be possible.
I'm all for BB for the same reasons as stated by Ben:
- easier maintenance
- higher flow
- eventually you can get a zoo covered floor
The ONLY advantage I can think of for sand is esthetics - it looks good. Its hit and miss to accomplish a good well-populated sandbed that is effective long-term.