I'm currently setting up my 55 gallon FOWLR tank and have two questoins: first one is can you use crushed corals with live sand as your substrate? Second do you have to use aragonite or any other "dead" sand with LS. I haven't made up my mind if I wanted to use really fine sand or go with the crushed coral look. I was thinking of adding around 20lbs of LS with whatever I decide to go with, does that sound like enough?