Hi
Sorry for the late response - haven't been on Fish Lore for a while.
I have specified many details in my blog when I was setting up the tank. These two links have all the info about substrate and all other stuff in the set-up:
http://www.fishlore.com/fishforum/isabella/5735-my-75g-journal.html
http://www.fishlore.com/fishforum/isabella/5658-finally-got-my-75g-o.html
And this is the blog link:
http://www.fishlore.com/fishforum/isabella/
Hope this helps
Isabella
P.S. Your account on Fish Lore seems to be blocked from receiving PMs, so I'm posting the response on your profile.