Today I brewed my 8th BIAB batch and with each one I've been suffering from low efficiency. Today's recipe was a Belgian Quad from AHS, which was a 15.5# grain bill. My volumes were fine according to BeerSmith, but my preboil gravity was 1.066 instead of 1.081, and my OG was 1.082 instead of 1.098. After an hour mash I did an iodine test and there was a good amount of purple, I mashed for another 40 minutes and the iodine test came out clear. I'm mashing in a 10 gallon kettle and I used 8 gallons of water, and the pH was at 5.3. Every AG recipe I've done has had around 60% efficiency and I can't figure out how to improve it.
Any ideas?
Any ideas?