I brewed this again Saturday (3rd time) and had an interesting brew session. First, I wasn't paying attention to how much pre-boil volume I had in my pot and sparged a little (even though I BIAB) extra water through the grain. I noticed I had about 8¼ gallons of wort. No biggie, I decided to boil an extra 30 minutes to bring the wort volume down. Let the wort boil 30 minutes then started my 60 minute hop addition and brown sugar and continued on. Boil complete, cooled to pitching temp, checked volume, only 5 gallons in my pot and the OG was 1.082, yikes. Siphoned into the fermenter only 4½ gallons of wort. I didn't panic just went inside and boiled another gallon of water. I needed some anyway to rehydrate the yeast. I added ¾ gallon of water to the fermentor to give me 5¼ gallons and I took another hydrometer reading. Now the OG is 1.074, much better, poured in the yeast and let it rip.