Davehenry said:
Thanks guys. I think I'm just going to go ahead and brew a 2.5 gallon batch and see what happens. I also asked a friend who has plenty more experience than me and he mentioned that the sweetness would go up as well. That might be okay for what I'm trying to accomplish, especially since beer smith raised the ibus for me.
I've even considers trying a parti gyle of the recipe but I'm still reading up on how to make that work. I've figured out how to calculate the OG of both runnings but still not sure how much water to use for each mash.
When you parti-gyle, the first runnings is your normal water calculations.
For the second runnings, you just add water at the appropriate temperature to be at about 168F in your Mash Tun. If you want, for example, 7 gallons in your boil in the boil pot, you need to run 7 gallons through it. No mashing is usually necessary for your second runnings, since the starch should all have already been converted to sugars in your first runnings. You're basically rinsing out the sugars. When I parti-gyle, I do my first runnings like a regular beer. Then I just stir in half of my second runnings, stir well and let it sit for about 10 minutes so that it disolves any sugars that may have started to set back up and crystallize on the grains. I lauter and drain. Then I put in the other half and repeat.
The only time you'd need to go through a mash again, is if you wanted to add more grain, either of the same grains as the original to up your gravity of your second runnings or to add different grains to hit a particular style you're after. You can save time though on this step too! When I decide to add grains for the second running, I do a mini-mash of those grains at the same time that I'm mashing my first runnings. After I've collected my first runnings and got them started boiling, I then pour my mini-mash onto my spent grains from my first runnings. You can then add about 3 gallons of water at about 170F, lauter and drain and see how much you've collected. Let's say that you now have 4 gallons collected. You then run 3 more gallons of 170F water through those grains and you now have your 7 gallons from your second runnings.
The most common issue that arises is undershooting your gravity on your second runnings. To fix this, just stir in the appropriate amount of DME of your choice to bring it up to what you want. It's usually not a very large addition of DME, so doesn't have a big affect on the final profile of your beer.
I've done straight second runnings with no grain or DME additions. I've done it with a mini-mash as described above. I've also added DME after measuring my preboil gravity and realized I'd be a little low. They all turned out good.
I did a huge Barley Wine once and made an English IPA with the second runnings. The English IPA won a blue ribbon at a brewing competition. I did a minimash of the same grains to up the gravity a bit on that one.
It's all fun though.
So, in a nutshell, I answered the water question. The other part is, don't be surprised if you come in low on your second runnings. Just have a plan ready, in case you do come in just a little low.