Originally Posted by briggssteel
Yea I used a calibrated PH meter so it's probably accurate. What can be expected with a PH this low?
I can't answer that question as I have never, in 30 years of brewing, managed to get myself into this situation. We can, of course, assume, that efficiency may be down but I wouldn't expect that to be by much. It isn't efficiency considerations that drive one to strive to hit a particular pH so much as it is the fact that at the right pH all the 'flavors become brighter'. I understand what that means in terms of pH too high (which I have experienced) but don't know what the effects would be if it is too low. Sub optimal, whatever that may mean.
Given that mash pH is too low you can certainly expect that kettle pH will be too low and a probable manifestation of that would be lower hops utilization. With the extra acidity the yeast will have an easier job of establishing the fermentation pH they want. Will they undershoot so the fermentation is impaired? Intuition says no - they will just secrete less acid than they normally do but I have nothing substantive to back that intuitive feel up.