Didnt have any dme. I ended up doing exactly that. I added 10 mins on the front of the boil prior to my hop schedule. I then checked gravities with my refractometer throughout the boil. 2 questions that came up. Does the gravity change after cooling? Does the volume?
With the added ten minutes I came within 1 point of my desired OG. Another question, if you add time on the back end doesnt that screw up the hoping on he beer?
All of this came up on this brew cause I just complicated things with a sight glass; trying to pin down volumes, boil off ect...on my equipment.