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Old 08-17-2010, 03:34 AM   #1
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Default Fermenting lagers in a Corny

The latest brewday conversation led to a discussion about whether you can ferment a lager in the kegerator. Size limitations would make it much better if the fermenter could be a Corny. I found a keg lid that's made for fermenting. It has an airlock attached.

Have any of you used this for fermentations? What's the maximum volume you can use? I'd imagine you can't ferment 5 gallons of lager in a Corny without clogging up the airlock.

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Old 08-17-2010, 04:36 AM   #2
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I'd do the primary fermentation in a conventional container, then rack it into the keg for secondary/lagering. Otherwise, you'll only net 3 or 3.5 gallons of beer: losses to trub and krausen will reduce your yield.

Or, you could do what many of the american brewers do to increase the effective utilization of their fermentors: make a higher gravity lager (~1.070), then dilute it down to an equivalent OG of 1.045 (or whatever) after primary fermentation. Several BJCP-winning lagers have been brewed this way in past competitions, though this technique is really only appropriate for american-style lagers (you might possibly get away with it for german pils and helles, too).

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Old 08-17-2010, 05:31 AM   #3
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You don't need the special keg lid, just attach a QD with tubing and airlock to the gas post or remove the post and attach tubing with airlock. Saves the cost of the special lid. I ferment most of my beer in a 15 gallon corny as the 5 gallon ones required that I split the batch into 2-3 cornies.

Many people use the plastic based ferm stop which keeps the foaming down so they can almost fill the keg. I never touch the stuff however.

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Old 08-17-2010, 11:40 AM   #4
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Couldn't you just let the pressure build up and purge it with the pressure relief valve?

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Old 08-17-2010, 12:22 PM   #5
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I ferment and lager in cornies and serve from them. The greatest part about fermenting and lagering is you can do a close system transfer. This will allow you to keep your beer unexposed from the time it hits the fermentation vessel to the glass.

I use 5/8th ID hose to go right over the IN valve with the popet removed.

m.

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Old 08-17-2010, 03:13 PM   #6
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Quote:
Originally Posted by prosper View Post
I'd do the primary fermentation in a conventional container, then rack it into the keg for secondary/lagering. Otherwise, you'll only net 3 or 3.5 gallons of beer: losses to trub and krausen will reduce your yield.
This is completely incorrect. I ferment exclusively in 5 gallon cornies. I get 48 bottles just about every time. My best yield has been 51 bottles. You can fill the keg up to the weld line at the top, then use fermcaps. Take off the out post and put a hose with a clamp on the threaded portion and you have a blow off tube.
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Old 08-17-2010, 03:35 PM   #7
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+1 with what TheMan said.

With a closed system transfer I have racking losses of about 400 to 500ml on 19L. That is about 3% loss. I always get some yeast transferred over into the lagering/serving keg, but I also transfer with 1 or 2 points left of attenuation. This cleans up anything that is left in the beer and they (the kegs) do not last long enough for autolysis .

The residual yeast in the serving keg is around 200ml and is only picked up in the first servings. After that is all clear.

m.

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Old 08-17-2010, 03:46 PM   #8
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Quote:
Originally Posted by prosper View Post

Or, you could do what many of the american brewers do to increase the effective utilization of their fermentors: make a higher gravity lager (~1.070), then dilute it down to an equivalent OG of 1.045 (or whatever) after primary fermentation. Several BJCP-winning lagers have been brewed this way in past competitions, though this technique is really only appropriate for american-style lagers (you might possibly get away with it for german pils and helles, too).
Granted I'm no lager expert, but I've never heard of this. First, after primary fermentation a lager, like an ale, has an FG of something like 1.010-1.020 (roughly speaking). I don't get how you would then dilute DOWN to 1.045...primary fermentation on its own should take the gravity way past that point. Is 1.045 a typo?

Second, assuming 1.045 is a typo, what is the benefit from diluting the fermentated product more than the FG? Third, how do you account for dilution of the IBU's? Do you overhop at the beginning?

I'm thinking you are confused....
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Old 08-17-2010, 04:02 PM   #9
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to an equivalent *OG* of 1.045, not FG. The FG doesn't matter here for the purposes of figuring out dilution rate

If your concentrated OG was 1.070, you would need to add about 50% water to get it down to 1.045. The fact that your adding the water after fermentation doesn't change the ratio

Dilution of IBU's isn't really a consideration for the styles of beers that this technique is used with as they don't tend to be particularly bitter or hoppy. But, it would be fairly simple to calculate out approximately 50% more IBU's in your concentrated fermentation, so that they would dilute down as well.

Read the first section of the article here for a more detailed explanation of the technique:
http://www.homebrewtalk.com/wiki/ind...ravity_Brewing
or here:
http://byo.com/component/resource/ar...ume-techniques

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Old 08-17-2010, 04:28 PM   #10
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Quote:
Originally Posted by prosper View Post
to an equivalent *OG* of 1.045, not FG. The FG doesn't matter here for the purposes of figuring out dilution rate

If your concentrated OG was 1.070, you would need to add about 50% water to get it down to 1.045. The fact that your adding the water after fermentation doesn't change the ratio

Dilution of IBU's isn't really a consideration for the styles of beers that this technique is used with as they don't tend to be particularly bitter or hoppy. But, it would be fairly simple to calculate out approximately 50% more IBU's in your concentrated fermentation, so that they would dilute down as well.

Read the first section of the article here for a more detailed explanation of the technique:
http://www.homebrewtalk.com/wiki/ind...ravity_Brewing
or here:
http://byo.com/component/resource/ar...ume-techniques

I see what you are talking about..thanks for the link.

Now I understand how BMC gets such a watery beer...they add water!
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