Head space

[Steve3730]

How much is enough? I have a 2 gallon bucket. Would 1.5 gallon brew be too much? how can you calculate how much headspace is needed.

 

[BrewWNC]

Determining how much headspace is too much or too little is really difficult as opinions differ and additional factors (type of beer, yeast, etc.).

Too much seems to be a factor for potential oxignization as there is more room for oxygen (if you continually open the fermenter over a period of time and/or transfer to a container that has a excessive amount of oxygen in headspace and ferment for a period of time).

Too little may result in quite the clean up.

I prefer too little to too much. But hey, you'll probably get different opinions.

 

[Qhrumphf]

1.5 gallons in a 2 gallon bucket will be fine. About 25-35% of the batch size as headspace is what I go for. In most batches it's enough to not need a blowoff, although sometimes still not enough and I need to affix a blowoff down the road. If you go less than 25%, that's fine too, but I would affix a blowoff from the start with every batch, period.

Many folks advocate using a blowoff right from the start on all batches period. If you're only using it for primary fermentation, the container size shouldn't be a big deal anyway as long as there's some headspace, as long as it's not a 1 gallon batch in a 6 gallon carboy (and even then, that might still be ok, not familiar enough with the science to say for sure off the top of my head)