Scaling up and diluting down

[FSUplumber]

My daughter ask me to brew the beer for her wedding this coming July. I am planning on brewing 3 beers. A pale ale, an American brown and a pre-prohibition lager. For the ales I am planning on boiling a 20 gallon batch splitting it three ways. After it fermetes out, rack it into cornys and push it into half barrels so the bar tender we hired can serve it to our guest. The problem is the lager. After discussing it with a close friend and a frequent poster, Mills. We came up with the idea of bumping the OG from 1.050 to 1.75 . Making two batches because my temp controlled fridge can only hold one 5 gallon batch at a time and then cutting it with pre boiled water to fill the half barrel. This would save me about 30 days of having my fridge tied up. I am planing on bumping the IBUs a little to make up for the higher gravity boil. Am I on the right track? What do yo think Tasty?

[BDawg]

Congratulations on your daughter's wedding!

I know I'm not the Great Tasty McDole, but that approach sounds reasonable to me.
Getting the IBUs right is going to be tricky, since hop extraction efficiency degrades the higher OG you go. You'll need to over compensate. Use your brewing software to figure out how to hit twice the IBUs in half the volume. (Then add a little more to be sure).

However, let's look at this from another angle. First, do you have lagering/conditioning space? Is this being driven solely by fermentation space? Or is it that you only have 1 small ferm chamber? If you use the same temp range yeasts, can you achieve the same thing and ferment/condition more beers at once?

Maybe you can use that same CAP recipe but ferment it with something like Wyeast 2112 which you can ferment at 58-60? That's the same temp that you can ferment WLP001 at, which will go great in your APA and Brown. All 3 can go into a fermentation chamber (google son of fermentation chiller) together and be treated pretty much equally. Maybe get a small used dorm fridge and build a fermentation box that connects to it (think along the lines of a huge horizontal collar), giving you more room to do these beers.

Just trying to throw alternatives out there for you.

HTH-

[FSUplumber]

Ya, my lagering is only big enough for a 6 gallon carboy. I like the idea of blending with an other yeast, my basement stays about 62 this time of year. Maybe a Kolsh yeast mix right in to it. Thanks

[BDawg]

I wansn't saying blend as much as use another yeast that can ferment at the same temp range

[Mills]

When we were discussing it we were kicking around the idea of scaling proportionately. I get the concept of taking ten gallons of 1.075 beer and cutting it to 1.050, but the IBU issue is what has me wondering.

Mills

[BDawg]

http://rhbc.co/wiki/calculating-ibus

Think about this as a problem of "how do I pack enough IBU particles / Flavor particles /Aroma particles into a batch so that when I dilute it, it will come out the same as if I brewed it at normal volume. So, since you are brewing a 1.075 batch instead of a 1.050 batch, it's 3/2 the gravity and therefore, you need the IBUs to end up at 3/2 the original value, too.
In other words, your target IBUs should be 3/2 the normal level IBUs, too.

The thing is that at higher gravity, you need to take that extra gravity into account, because your utilization suffers.

I figure if you formulate it for 3/2 the IBUs in 2/3 the volume using the Rager formula which has the gravity adjustment GA which is (1 + ((OG - 1.050)/.2))

IBUcondensed == 3/2 IBUnormal (so if you are targeting 50 ibus, that would be
3*40 / 2 = 75 IBUs condensed

where Wnormal = Weight in oz
%AA = Alpha Percent of the hops
Utime = Utilization for a given time in the boil
7489 = a constant that adjusts this from metric into US units

50 IBUnormal = (Wnormal * %AA * Utime * 7489) /
(15 * (1 + (1.050 - 1.050)/.2))) <== the GA goes to 0 so the bottom part of this fraction is 15.


So, using the table for Utilization at Boil Time (Utime):
.3 at 60 mins
.08 at 15 mins

If we assume that this batch will use 12% Magnum at 60, 4% Sterling at 15 (and 0),
you will want the sum of their additions to add up to be 60 IBUs (in the thicker wort).

Let's start with the 15 min addition. If this was a 15 gallon batch of CAP, I'd be thinking along the lines of 6 oz of Sterling at 15. (ie, I'd be adding 2 oz per 5 gallon batch)

IBU 15 condensed = (6 * .04 * .08 * 7489) / 11.25 = 12.78 IBUs
75 - 12.78 = ~62

In order to add 47 IBUs from bittering, we solve for that weight:

W60condensed = (62 ibus * 11.25) / (.12 * .3 * 7489)
W60condensed = oz or about 2.65 oz

So, you want to hop it with:

2.65 oz of 12AA Magnum at 60
6 oz of 4 AA Sterling at 15
another 6 0z at flameout,
then Dry hop the fuck out of it, esp after you re-dilute

HTH-

[edited to hit 50 Target instead of 40 target which was low for the style]