How little in a 25L fermentation vessel?

[jezbrews]

So I bought a 15L vessel for smaller batches but ****** up the hole size and now it leaks, despite using larger silicone washers. I might be able to find a work around, but in case I don't I do have a trusty old (not that old) 25L FV, but of course there's a risk with a lot of head space (what with CO2 blankets not being a real thing) so how small a brew can I make in one before accepting I need a smaller fv?

 

[phildo79]

What is the risk with a lot of headspace? If it's airtight, surely any oxygen will be pushed out over the duration of fermentation, no?

 

[The Baron]

Phil is right plus if the seal is not perfect on the 15l FV you can still use it as the co2 will just escape and may not go through a airlock if fitted. Some people just use clingfilm as a cover and some brewers even go with no top so it is still usable from what you have said put some cling film over it and make a small hole in it for gas to escape if you have to

 

[Agentgonzo]

IIRC, every two gravity points give you a volume of CO2. So even a weak beer will evolve many times the volume of your fermenter in CO2, pushing out there oxygen.

Remember that people still ferment in open fermenters where there is essentially an infinite headspace.

 

[Agentgonzo]

Phil is right plus if the seal is not perfect on the 15l FV you can still use it as the co2 will just escape and may not go through a airlock if fitted.

Unless he's meaning that the beer leaks.

 

[The Baron]

Yes after re-reading it you may be right Agent?
I wonder if he had drilled for a tap now?

 

[foxy]

Yes, seems his stuff up was on the tap hole. There are taps with different size threaded spigots. To answer the question, the rule of thumb is around 20% head space for a fermenter is minimum. Don't think there is a maximum as mentioned it will fill easily with co2.

 

[jezbrews]

Phil is right plus if the seal is not perfect on the 15l FV you can still use it as the co2 will just escape and may not go through a airlock if fitted. Some people just use clingfilm as a cover and some brewers even go with no top so it is still usable from what you have said put some cling film over it and make a small hole in it for gas to escape if you have to

Not sure what you mean by using cling film. How is that going to hold back the pressure of 15L of beer?

 

[jezbrews]

Yes after re-reading it you may be right Agent?
I wonder if he had drilled for a tap now?

This!

I am still here though, you can ask me rather than using the third person lol

 

[jezbrews]

.

 

[foxy]

Not sure what you mean by using cling film. How is that going to hold back the pressure of 15L of beer?

Doesn't hold back pressure but releases pressure much the same as an airlock. As you can see he didn't leave enough head space in the fermenter.

 

[Sadfield]

Remember that people still ferment in open fermenters where there is essentially an infinite headspace.

Let's be clear on this. Open fermentation is only done whilst the yeast is actively producing lot CO2. The beer is then covered or transfered to a closed vessel. The headspace should be considered, as the closed vessel headspace. A lid and an airlock is an automatic way of doing this, acting as a non-return valve allowing the venting of CO2 into that same 'infinite' headspace. Open fermentation is more to do with surface area and speed of off gassing of CO2, as dissolved CO2 reduces ester production. Ester production is largely completed in the first couple of days of fermentation. For higher ester production, open ferment. For suppressed ester formation, ferment under pressure.

 

[Stevieboy]

(what with CO2 blankets not being a real thing)

eh?

 

[AJA]

eh?

It's one of home-brewing's most bizarre myths. It's not even intuitive, so I'm unsure has it has come about. Gases mix.

 

[jezbrews]

CO2 may be denser than oxygen, but the difference is insufficient to make much of a difference. We'd have died of oxygen toxicity if gases layered!

 

[jezbrews]

Doesn't hold back pressure but releases pressure much the same as an airlock. As you can see he didn't leave enough head space in the fermenter.

View attachment 81401

My leak is around the tap, which I cut a hole for, not the lid.

 

[foxy]

My leak is around the tap, which I cut a hole for, not the lid.

It had already been established the leak was around the tap. It was you who asked the question what was cling film for as the baron mentioned it. That is what cling film is used for, replacing a lid.