I brewed up a quad today, completely missed my pre-boil SG/volume and am trying to figure out where I went wrong. Info is below, and I wound up hitting my targeted OG with an extended boil/addition of roughly .75lbs of DME. I'd appreciate any help you guys can give, a few of my recent brews were a bit lower than expected and I'm trying to understand what I'm doing wrong.
16lbs Belgian Pale
4lbs Maris Otter
1lb Special B
Mash ratio: 1.25qt/lb
Mash at 154f for 75minutes w/27.25qt (I hit 154f exactly on this)
Batch sparge w/15.5qt
First runnings= 1.083 (hydrometer was calibrated/verified immediately prior to reading)
Second runnings= 1.040
Pre-boil OG= 1.064 (Targeted was 1.090)
Boil volume= roughly 8.5 gallons (targeted was 7.48 gallons)