Marco...that's the one they were talking about.  Looks like they have less of a leaching problem than the BRS Pukani.  I might have to give them a try.
I know the rock = 1 to 1.5 x water volume isn't a set rule, but using that as an estimate would I use the water volume of my DT or the volume of my DT+sump+fuge?  
My DT is going to be 120g, remote sump 90g, and remote fuge 75g.  So that's a pretty big difference between 120-180lbs vs. 285-427lbs.