Here it is
http://www.manhattanreefs.com/forum/general-discussion/149404-black-sand.html
Ive had it on my 20 gal for very long, no issues. Had it on my 80, liked it. Just switched to white now because i had an emergency(nephew threw play dough in my tank killing lots of corals overnight) and i ran to the lfs and only found white(which i like too).
The main thing is there is three types of black sand.
1- A really fine one that is horrible, makes a mess and goes in your pumps;
2- another (hawaiian black by caribsea )which is ok, but the new batches are coming with lots of fine white mixed on the bottom of the bag, and the size of the sand is kind of fine too which makes it a bit messy, /you end up with a black/white look
3- the one ive had before which is also caribsea, but the grains are larger, sort of like small pebble size. They are pitch black and the appearance is awesome. They used to come more in the small 10lbs bags, and when i ordered that size, the right kind would come. When i ordered 20lbs, the fine/white sand mixed one would arrive...
Here is a pic of my tank with it on its best days, around 6 months after the tank was set up:
This is the kind you want, with bigger granules
When i had it in my 80 Gal:
If my LFS had the right black type when i went looking after the emergency WC, sand change, i would 100% ditch the white for it.
But if it is not the correct kind, dont do it. Just like with anything in this hobby, you must really look for what you want. Sometimes it pays off. The color pop with black sand is unmatched.
Hope that helped!