I bought some of the black diamond blasting sand today. It was such a great price $14 for a 100 lb bag. I'm going to be able to do at least six of my smaller tanks with it! Anyway, that's not the point. I really like the blue contrast on the black and really happy with the way they look on it! I actually used a bit of it with my new pair of powder blue dwarf gourami I acquired today and it look stunning with them as well.