Originally Posted by anth
Just a thought, but perhaps your wort wasn't properly mixed during one of the samplings?
The odd thing is, that the pre-chill gravity would be the one that I could have messed up with insufficient mixing. But I did mix it well and it also makes sense if I look at the numbers:
pre boil gravity = 15.3 Plato; volume = 25 l
post boil/ pre chill gravity = 17.0 Plato; volume = 22 l
If I predict the post boil gravity from the preboil I get 17.4.
The post chill gravity of 16.0 Plato for 22l just doesn't fit into the picture.