Boil volume and IBUs - Home Brew Forums
Register Now For Free!

Home Brew Forums > Home Brewing Beer > Beginners Beer Brewing Forum > Boil volume and IBUs

Reply
 
Thread Tools
Old 03-08-2011, 09:58 PM   #1
binkman
 
binkman's Avatar
Recipes 
 
Feb 2011
Baltimore, Maryland
Posts: 490
Liked 10 Times on 6 Posts



Hi all. I'm missing something.

So I brewed my first batch from a kit, and now I'm ready to dive in way over my head. And I have.

I'm brewing a batch without a kit, and I have piped all the information into some brewing software. I thought it was all fine, until I started tinkering with the boil volume. Now, everythings wonky.

Previously, I had an IBU value of around 22. The program was assuming that based on a 6.08 gallon boil, however. I have a 6-gallon brew pot and a 6.08 gallon boil seems more than a little impossible. The recipe I made from the kit called for a 2.5 gallon boil, then I added water.

Ok fine, so I have to increase the hop boil amount/time ratio to increase IBUs. I get that. But I feel like I'm missing something: I put in the kit's recipe and ingredients into my software and guess what? Everything was fine until I adjusted the boil to a 2.5 gallon boil like the instructions said. When I did that, the 10-13 IBUs they were saying I would end up with dropped to 6. Is the kit wrong? Is the program wrong? Or am I failing to take something into consideration? I don't want to brew a 5-gallon batch of underhopped beer, if another coupe ounces can make all the difference. At the same time, I don't want to overhop it. I'm shooting for a style calling for 20-28 IBUs.

Any help would be appreciated, thanks!

 
Reply With Quote
Old 03-08-2011, 10:04 PM   #2
ayoungrad
Recipes 
 
Sep 2010
Tampa, FL
Posts: 1,102
Liked 12 Times on 12 Posts


Try putting the info into some online free calculators.

I like:

http://www.fattymattybrewing.com/hom...s&action=entry

because it uses 3 separate ways of calculating IBUs.

I use my own spreadsheet now which also calculates IBUs several ways but I've found Tinseth's calculations to gel best with my tastes.

Not sure why the numbers are different from those in the kit. Do you have the AA% correct? Did you enter the boil times exactly as written? Did you adjust for volumes at the start of the boil and for the final volume after topping off?

 
Reply With Quote
Old 03-08-2011, 10:11 PM   #3
binkman
 
binkman's Avatar
Recipes 
 
Feb 2011
Baltimore, Maryland
Posts: 490
Liked 10 Times on 6 Posts


Quote:
Not sure why the numbers are different from those in the kit. Do you have the AA% correct? Did you enter the boil times exactly as written? Did you adjust for volumes at the start of the boil and for the final volume after topping off?
The AA is correct. Even messing with it, though, it'd have to be way off to make up for the difference.

Boil times exactamundo.

Adjusting volumes check. Actually, I didn't add the volume of the liquid extract to the 2.5 gallons of water the kit recipe called for. Could this be the problem?

 
Reply With Quote
Old 03-08-2011, 10:13 PM   #4
binkman
 
binkman's Avatar
Recipes 
 
Feb 2011
Baltimore, Maryland
Posts: 490
Liked 10 Times on 6 Posts


In fact, adding the LME volume, which i assume to be about 10 fl oz. to the lb., brings it back almost within the correct range. Kit would yield 9.3 IBU, kit recipe calls for final IBU of 10-13.

 
Reply With Quote
Old 03-08-2011, 10:14 PM   #5
aggiejay06
Recipes 
 
Sep 2009
Cary, NC
Posts: 209
Liked 2 Times on 2 Posts


What software you using? Beersmith?

 
Reply With Quote
Old 03-08-2011, 10:16 PM   #6
ayoungrad
Recipes 
 
Sep 2010
Tampa, FL
Posts: 1,102
Liked 12 Times on 12 Posts


There can be pretty big variation in the 3 dominate ways of calculating IBUs. The kit may use a different one and that could certainly correct the little bit of difference you have left after the LME.

 
Reply With Quote
Old 03-08-2011, 10:17 PM   #7
brewit2it
Recipes 
 
Jan 2011
Glendora, CA
Posts: 862
Liked 15 Times on 14 Posts


Quote:
Originally Posted by binkman View Post
The AA is correct. Even messing with it, though, it'd have to be way off to make up for the difference.

Boil times exactamundo.

Adjusting volumes check. Actually, I didn't add the volume of the liquid extract to the 2.5 gallons of water the kit recipe called for. Could this be the problem?
No. It is 80% solids so the water volume isn't going to be significant. Why don't you list your planned hop schedule?
__________________
See my cheap new Keezer Build Here:
http://www.homebrewtalk.com/f51/chea...keezer-224848/

Primary: 2 Row IPA
Second Primary: Kolsch-like ale

Keg 1: Blur Moon
Keg 2: Empty
Keg 3: Empty

Bottled: None

 
Reply With Quote
Old 03-08-2011, 10:29 PM   #8
binkman
 
binkman's Avatar
Recipes 
 
Feb 2011
Baltimore, Maryland
Posts: 490
Liked 10 Times on 6 Posts


Okay, so the kit broke down like this:

Steep 1 lb specialty grains in 2.5 gallons of water for 20 minutes, then add 6.6 lbs of extract and begin boil.

Boil schedule: Add bittering hops (.5 oz at AA 4.5). After 40 minutes add flavoring hops (.25 oz at AA 4.2). After 20 minutes terminate boil. Cool wart, add enough water to make 5 gallons.

Program claims there will be 6 IBUs.

IBUs: 10-13, OG: 1049-1053, FG: 1012-1015, ABV: 4.75-5.25.

My recipe:

Steep 1.75 lbs specialty grain in 2.5 gallons of water for 20 minutes. Then add extract start boil.

Boil schedule: Bittering hops (1oz at 4.3 AA) 60 min from end, then flavoring hops (.5 oz at 3.3 AA) 30 min from end, then aroma (.25 oz 3.5 AA) 10 min from end. This leaves me with 11.5 IBUs.

If I increase the boil volume to 6 gallons, assuming I lose 1 gallon and don't have to add anything to my boil afterward, I get 20.8 IBUs.

PS, I'm running a mac and using BeerAlchemy.

 
Reply With Quote
Old 03-08-2011, 10:35 PM   #9
binkman
 
binkman's Avatar
Recipes 
 
Feb 2011
Baltimore, Maryland
Posts: 490
Liked 10 Times on 6 Posts


Quote:
Originally Posted by ayoungrad View Post
Try putting the info into some online free calculators.

I like:

http://www.fattymattybrewing.com/hom...s&action=entry

because it uses 3 separate ways of calculating IBUs.
My average IBU strength for my boiling schedule and 2.5 gallon start volume comes out to 44.9, (43.1 tinseth). This is of course the pre-diluted IBU. But why is my program so wrong? I've triple checked everything else.

 
Reply With Quote
Old 03-08-2011, 10:55 PM   #10
ayoungrad
Recipes 
 
Sep 2010
Tampa, FL
Posts: 1,102
Liked 12 Times on 12 Posts


I want to make sure I am understanding your issue.

You get 20.8 IBU for a full boil with your calculator.
You get 11.5 IBU for a partial boil with your calculator.
You get 44.9 IBU for a partial boil (before topping off) with the online calculator which then corrects to 18.7 adjusting for volume.

Is this correct?

If so, the online and full boil BeerAlchemy calculations agree but the BeerAlchemy partial boil does not? Is this correct?

 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Boil Volume jderm Beginners Beer Brewing Forum 2 08-09-2010 01:53 AM
Trouble getting the right IBUs out of Beersmith for a Partial Boil JerTheRipper Beginners Beer Brewing Forum 3 05-15-2010 01:34 PM
boil volume? foxual Beginners Beer Brewing Forum 7 07-08-2009 08:01 PM
Help! Include LME volume in boil volume? bitteral Beginners Beer Brewing Forum 7 05-31-2009 06:30 PM
Boil Volume daveofmacomb Beginners Beer Brewing Forum 3 04-30-2009 02:25 AM


Forum Jump