Hi Learned folk. Quick question I'm a BIAB with mixed results at the moment. For Brewers friend it has estimated boil size, then batch size. I've taken this to mean what I start with pre boil, that batch size is after I top it up with water? Boiling with 17 litres of wort at the moment, than 12 litres normally makes it into the fermentor than normally top up to 18 litres or so depending on the refractometer. Thanks folk.