I began extract brewing about a year and a half ago, and I gotta tell ya, I love this hobby. But to the point. I know the instructions say to begin the boil with 2.5 gal of water. I did that for the first couple of brews, but then began to increase the volume to 3.5 gal because, well, I could, and to be honest I didn’t really notice a difference in taste. Maybe that’s because I didn’t really have much to compare it to. But I’ve seen on here that if you do increase the boil volume, you may want to adjust your hop schedule. What adjustments would one need to make?
When you switch from a 2.5 gallon boil to a 3.5 gallon boil you are reducing the gravity of the wort in your kettle. The generally held belief is that the amount of bitterness you extract from hops increases as your wort gravity decreases.
So, what this means is that to achieve the same level of bitterness in your final beer you need to use fewer hops in the 3.5 gallon boil. This impact isn’t huge. There are some bitterness calculators out there online that you can use to dial things in better (search for hop utilization calculator), but as a general starting point you might want to decrease you hop additions about 10% by weight for a normal gravity 1.050 beer. You probably only need to adjust your bitterness (60 min) additions. I wouldn’t worry much about adjusting your late aroma additions since they don’t contribute much bitterness to the finished beer.
The difference in bitterness here may only be a few IBU’s so in the end you may not be able to tell much difference in the taste of the final beer.
The Homebrew Nerd
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