Yeah, 5:3 if you're dosing with Calcium chloride. I can't remember what Ben premixed mine out at but I thought it was that, but who knows. It's probably explained in his thread somewhere buried behind the 100 pages of "To to top" posts.
Found this nice synopsis of 5:3 vs 10:1 here
http://www.reefcentral.com/forums/sh....php?t=1685138 which then references the RHF articles.