Best black cap for dirt tank?
I am planning on doing a dirt tank (a walstad tank). I want a black cap, but really want something natural looking. I saw all the tanks on here with black diamond and they look good, does it make for a good cap? The black gravel at my LFS is just way to big, they would look like boulders.
I am wondering what everyone like to use and could recommend?
Pics wouldnt hurt either