Using Black Sand

[ALang]

Don't think that it's sharp.
Watched a marine show on Raja Ampat, and some parts of their ocean floor is black volcanic sand. We saw critters and fish like jawfishes, ribbon eels, shrimps and burrowing squids etc doing just fine.
As for the buffering capacity, and Calcium/alkalinity levels, you can always dose bulk calcium and soda ash, using a couple of auto-dosers. More reliable anyway.
I think that black sand is great looking for a small tank.