The boil.
Interestingly the pre boil gravity were both exactly the same. Final gravity the BM which lagged behind the boil of the Guten came out at 1,051 and the Guten 1,048. theoretically should both have been the same
My last few brews have been full volume mash in the Guten and my efficiency has suffered a lot, my last brew was supposed to be a 7.2% IPA that's come in at 4.9%, a nice beer but I'm now calling it a 'session IPA'
Never a dull moment in this game, always something new to try.