problem if fermentation receptacle is much larger than batch?

[tomaso]

Quick noob question: Is it a problem if the fermentation receptacle (be it plastic or glass) is much bigger in volume than my batch?
I.e. can I ferment a 5l batch in a 20l fermentation receptacle?


If it is a problem, why so and what should be the maximum difference between the two?

Thanks!

 

[DSorenson]

I could imagine using half the volume of the fermenter, giving you ample headspace for some yeasts that require it, but more than that doesn't make sense to me. It's probably not bad in the short term, but in the long term I cannot imagine it will be good.

 

[Cyclman]

For primary, no problem, but secondary it will oxidize.

 

[DSorenson]

For primary, no problem, but secondary it will oxidize.

Somehow I forgot to mention this... but THIS!^^^

 

[tomaso]

Thanks guys!
Just to check: The problem is that while in primary all the oxygen in the large head space will be used by the yeasties to get a good initial start while in secondary the same oxygen would also be taken up by the yeast but this time would lead to unwanted aeration=danger of beer going stale.

Is that right? Also, would there be off flavors as well or only danger of beer going stale?

Thanks!

 

[RM-MN]

Thanks guys!
Just to check: The problem is that while in primary all the oxygen in the large head space will be used by the yeasties to get a good initial start while in secondary the same oxygen would also be taken up by the yeast but this time would lead to unwanted aeration=danger of beer going stale.

Is that right? Also, would there be off flavors as well or only danger of beer going stale?

Thanks!

During primary fermentation the majority of the O2 will be expelled through the airlock, not used by the yeast. As soon as the yeast start to eat the sugars and create CO2, the heavier CO2 will cover the beer and no more O2 will be available to the yeast.

If you move the beer to secondary after CO2 production has ceased, there will be little CO2 to provide the protection from the O2 to the beer so it will oxidize or if your sanitation isn't good enough will cause the beer to spoil from the bacteria present in the air. Many of the potential spoiling bacteria require oxygen so a good cover of CO2 protects your beer.

 

[Rsfreitas]

I'm having the same problem because I can't find a decent 12L fermenter with tap and airlock.
So I thought about a potential safety measure to remove oxygen from the fermenter... Co2 Pump.
Amazon has some cheap ones people use for bike tyres..
Do you think that would solve?

 

[unionrdr]

With two different stories claiming to be correct- One side claiming the Co2 pushes the O2 up & out the airlock- & the other side saying, no, the Co2 absorbs the O2 until excess pressure blows out the airlock, I thought of a neat experiment. If we could get our hands on a sensor rig to put in the fermenter that'd sense what gasses are present from the surface of the wort to the top of the fermenter near the airlock stem, rigged to something that'd read the sensor over time, we could find out what's actually happening.
I'm sure most of us would like to settle this argument once & for all?

 

[Stillraining]

With two different stories claiming to be correct- One side claiming the Co2 pushes the O2 up & out the airlock- & the other side saying, no, the Co2 absorbs the O2 until excess pressure blows out the airlock, I thought of a neat experiment. If we could get our hands on a sensor rig to put in the fermenter that'd sense what gasses are present from the surface of the wort to the top of the fermenter near the airlock stem, rigged to something that'd read the sensor over time, we could find out what's actually happening.
I'm sure most of us would like to settle this argument once & for all?

I guarantee you it CO2 does not absorb O2..It displaces it.

I have pulled quite a few 10.000 gal service station fuel tanks needing replacement...we displace all the O2 from the tanks using dry Ice in water.. check for presence of O2 with a sensor and then we then cut large holes in the tanks right on site with gas hatchets to get access to the inside to clean them of any remaining liquid gasoline still in them that we could not pump out.

No O2 no explosion.......a little nerve racking the first time you do it.

 

[TheBrewingChemist]

I guarantee you it CO2 does not absorb O2..It displaces it.

Second that.

 

[Rsfreitas]

Me too.
CO2 is heavier than O2 and air, so it goes down. That's the reason a proper growler filling station fills the bottle with co2 first... It remains inside the bottle and is pushed out by the beer, which will never touch the air.

 

[ncbrewer]

Here are a couple of links that discuss mixing of gases:
[ame]https://www.youtube.com/watch?v=_oLPBnhOCjM[/ame]
http://colinb-sciencebuzz.blogspot.com/2010/01/if-co2-is-so-heavy-why-doesnt-it-sink.html

From these, and some other sources, I'm convinced that the gases mix, but not really fast.

 

[unionrdr]

That's why I mentioned both sides of the Co2 argument. Some say it diffuses, albeit slowly.