Good luck and let us know how it works out. I've been interested in Flourite Black Sand myself but don't currently have a tank I can put it in.Ok, thanks for the replies-I guess I'll get it then. Sorry about the spelling on the title-I did spell it right in the message though-I suppose I should proof read these a little better.
Two bags of regular flourite provided 3-4" in the bottom of my 20 gallon long; one bag in a 20 should be more than enough for what you're trying to do.20 gal high. Btw, how many bags do you think I need? I'm hoping I only need one, otherwise I suppose I'll have to live with my current substrate for now.