hello all. I have a question about adjusting hop bitterness in a small batch with late extract additions. In a few days I'm gonna brew a small all-grain 2 3/4 gallon batch of sweet stout, in my effort to experiment with a sweet chocolate stout.
If I were to mash all the grains at once and boil full volume, I need about 3.6 gallons water pre-boil, and my recipe calculates to 31 IBU, according to Beersmith. However, I was planning to take a gallon of water and cold steep my dark grains, and add it to the boil with 15 minutes or so left. So I'd start with 2.6 gallons, and I'm guessing I'll end up fairly close to my final volume when I'm done.
So I adjusted my batch size in Beersmith to 1 3/4 gal, and it changed my predicted IBUs to 41. I'm not looking for a strongly hopped beer. Should I reduce my hop additions to get back to 31 using the smaller boil, or just leave them as-is? Am I going about the calculations in the wrong way?