Thanks Denny, I'd seen the link (I think you posted it) but it hadn't worked for me before.
Kai I'm not sure what you're saying. Yes there are a number of variables that affect conversion efficiency, I think its reasonable to think that for a given set of conditions, a thinner mash would convert slightly better than a thick mash. Maybe its not the case, I'm really not even sure why a thinner mash would give better conversion. I wouldn't have predicted it. It would be interesting to know the machanism, someone mentioned a postive effect on gelatinization and that seems reasonable.