I could be wrong, but I think that of the smaller (250ish gph) most don't have recirculation pumps, so doubling the sugar content is the most efficient, though you could go to 6-8 in one pass if you don't mind running a little slower. BUT there are a few with recirculation pumps that will go to 10-12 in one pass. Off the top of my head, I think the cdl 250, the lapierre 250 and maybe MES or Memprotec have a model set up like that. You can probably tell by price. The leader micro 2 is under $4000. I think the cdl 250 is over 6.