Fermenting in a 7.9 Gallon Primary

Ingredients
1

Fellow Brewers,

I’ve decided to try my hand at brewing 7.5 gallon batches and kegging in the new slim quarter kegs.  However I obviously cannot fill a 7.9 gallon primary with 7.5 gallons of wort and not expect something to blow up or at the very least have half my yeast go through the blow-off tube.

How much headspace would you recommend in the 7.9 gallon fermenter?  I was thinking about brewing 6 gallons to a higher OG and adding a gallon of water when I keg.  Thoughts?

Dave

2

I would brew 6 gallons and just put that in the keg, or brew more and use fermcap.  I would not dilute it with water.

3

Curious as to why not add water?

4

I’ve diluted with water post-ferment without issues. Usually I do this when I overshoot my OG on brew day, and don’t have time to sterilize top-off water right then.

5

If you do add water post-fermentation I would add sanitary, de-aerated water.  (Boil and let cool.)

6

Thanks.  That’s a great point.  I didn’t even think that the water would be oxygenated coming out of the faucet…

7

Mostly because I formulate recipes for a non-diluted batch, going more concentrated will have some effects on hop utilization and fermentation profile.  If you want to play around with it that’s cool, it’s just not what I would do.

8

Tom,

I see your point.  Do you think I could get away with 7 gallons and just let the Krausen blow out?  Or do you think that would be detrimental to the beer?

Dave

9

Letting it blow out is fine, but you might lose more than you want to with a really full fermenter.  You can always build an expansion chamber for your fermenter too :)  Think of it like a sanitized funnel that you stick in the neck of a carboy and cover with foil - it will give room for the krauzen to form, but it will drain back into the carboy so you don’t lose as much.

10

VERY cool idea man!  :wink:

I may have to play with that one…