How Full A Fermenter?

[kfahy]

Hi all,

I am looking to experiment with different types of yeast. Basically i will make a large batch or wort and split into different fermentation vessels, pitching each with a different yeast.

I will probably punch out about 45L or wort or so, maybe a bit more depending. I have 30L vats, no smaller flasks or anything.

I am wondering if there are likely to be any issues if i only fill the 30L vat to about the 15L mark or so, or even lower? I kind of figured it wouldn't be an issue during primary but i was wondering about racking and secondary ferm. Will there be too great a risk from all the likely oxygen or should i just not rack, or just ensure i do it early enough to make sure there is enough fermentation left to go that a nice co2 blanket will form in secondary?

Any advice would be appreciated.

And for interests sake i am making a Pale Ale. Will probably pitch with 1028 -London, 1098 - British, 1968 - London ESP and am intrigued by some others too. I am not restricted to Wyeast at all but i have access to the above. What are some favourite yeast for a PA?



Thanks in advance.

 

[raven19]

If your sanitation is up to scratch you won't have an issue.

Once your beer has been moved into a secondary vessel the alcohol will provide some immunity. Preferably rack when you have a day or so to go to reach FG, giving you that extra CO2 blanket of protection.

The best advice I could give it pitch an active firing starter suitable for your wort volume.

1469 in a Pale Ale is also good, but start with your 3 then go from there. 1056 will give you a clean ferment.

 

[Nick JD]

I often underfill fermenters. My best (worst) was 8L in a 30L fermenter - friends asked me if it had leaked. No issues - and zero chance of foaming out the airlock!

EDIT: for some reason the fermentation seems quicker, even if the "correct" amount of yeast is pitched. Dunno why.

 

[RobB]

I think your concerns here are justified and you've already picked the two best solutions:

Will there be too great a risk from all the likely oxygen or should i just not rack, or just ensure i do it early enough to make sure there is enough fermentation left to go that a nice co2 blanket will form in secondary?

For a pale ale, I would simply not rack. Leave your ale in the primary for a couple of weeks and the risk of autolysis is spretty much nil, but the risks of oxidation from a secondary vessel half full of fresh air are much higher.

As others have pointed out, the low volume in the primary isn't a concern. When you prime your bottles, you add a small amount of sugar and your beer is carbonated to say 2.5 volumes. That's 2.5 full bottles worth of CO2 at atmospheric pressure. Now consider how much sugar is in your wort and you can see that your head space in the fermenter will be displaced by CO2 many times over.

Good luck with the experiment.

 

[jbowers]

I think your concerns here are justified and you've already picked the two best solutions:



For a pale ale, I would simply not rack. Leave your ale in the primary for a couple of weeks and the risk of autolysis is spretty much nil, but the risks of oxidation from a secondary vessel half full of fresh air are much higher.

As others have pointed out, the low volume in the primary isn't a concern. When you prime your bottles, you add a small amount of sugar and your beer is carbonated to say 2.5 volumes. That's 2.5 full bottles worth of CO2 at atmospheric pressure. Now consider how much sugar is in your wort and you can see that your head space in the fermenter will be displaced by CO2 many times over.

Good luck with the experiment.

Sorry to thread steal, but it sort of relates - if one wanted to cold crash in the primary for say 4-7 days, would storing it at low temps around 2-5 degrees prevent autolysis occuring after the 2 weeks already in the primary?

 

[RobB]

Sorry to thread steal, but it sort of relates - if one wanted to cold crash in the primary for say 4-7 days, would storing it at low temps around 2-5 degrees prevent autolysis occuring after the 2 weeks already in the primary?

So three weeks in total on the yeast? Autolysis won't (or at least shouldn't) be a problem in this time frame at any reasonable temperature.

 

[jbowers]

I was under the impression that Autolysis would be delayed further by having the wort at very low temperatures. Is this so?