Today I attempted an American IPA (Extract) full boil.
I calculated the OG to be around 1085 using beersmith. The recipe included just over 11lbs of fermentables (9.15lbs LME, 1.10lb DME, 1lb corn sugar).
Somehow the OG came out low, around 1070-1072.
The only thing I can figure is that because of the massive amount of hops I added there was a significant amount of sludge in the bottom of the brew kettle. It was impossible to filter all of this out to get it to the fermentor, resulting in me leaving it behind and topping the fermentor off w/ between 1/3 to 1/2 gallon of water to reach 5 gallons. Could this cause the lower Gravity reading? Otherwise I am stumped.