Keg fermentation headspace

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Djangotet

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Hello, I plan to ferment in a 2.6 gallon keg. I want to link it with an empty keg that has a spunding valve to keep about 10psi of pressure. Am I able to ferment a full 2.5 gallon batch or should I dial back to 2 gallons? Thanks?
 
I'd definitely "dial back" from 2.5 gallons, the question is how much.
If the OG of this brew is modest (say 50 points or less), the temperature is controlled, and the strain used isn't known for histrionics (eg: S04 if allowed to warm) 2 gallons might work ok...

Cheers!
 
I'd definitely "dial back" from 2.5 gallons, the question is how much.
If the OG of this brew is modest (say 50 points or less), the temperature is controlled, and the strain used isn't known for histrionics (eg: S04 if allowed to warm) 2 gallons might work ok...

Cheers!
Sounds good, thank you
 
I fermented 70 2.5 gallon batches in 5 gallon kegs and had kruesen in the airlock several times. Seems to me this was the right amount of head space. Kept the keg in my fermentirator (temperature controlled refrigerator) and used a PicoBrew Z and with a shortened dip tube. I wised CO2 to force it out into bottles.
 
I ferment 4 gallons in a keg all the time. When using a yeast that makes a really big Krausen (like Verdant) I back off to 3.5 gallons. I purge the dry hop and serving keg at the same time, running tubing between them and then into a jar of StarSan. I haven’t tried spunding yet.
 
I do not have much experience, but there is a product called fermcap that might help with fermenting with tighter headspace.
 
I've been fermenting 5 gal in a 5 gal keg with no issues so far. there is about 0.5 gal headspace in a corny. a 5 gal corny hold 5.5...so I assume your 2.6 corny holds 3.1 total volume.

I've not had any issues fermenting full "rated" volume. Well the exception being a hefe. But even that did nothing other than blow krausen out the blow off tube, not any beer loss.
 
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