i've been using the black sand blasting sand for about 6 months and I'm very happy with it. I've had a brown algae bloom for a week maybe because of the silica? but i just stir the sand twice a week every water change and it disappeared.
i used blasting sand like that before, turtle eats and poops it, she is fine from it but i don't like it cause it's too rough, scratches the glass and what not.