I brewed a decocted Altbier a couple of days ago. In my water calcs I overlooked the evaporation that took place during the decoctions, and ended up with less wort (and a higher gravity) than I’d intended for.
I didn’t think to top it up with water prior to fermentation, which is already well under way. Does anyone have any light to shed as far as topping up (with boiled water) post fermentation?