odedald

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Hi everyone, im about to brew my 2nd time and got some questsions:

1. Is there a probleme fermenting 10L in a 25L tank?

2. If i let the 1st fermentation keep going, and it has passed the FG i wanted (for example i wanted 1.013 but got 1.008 all because i let it lay for a longer time because of my lack of free time.)
Could i change the FG by adding corn sugar? or at least will it be ok to do that regarding the final product?

Thanks for your help

basilchef

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1 you risk oxidation. I think.
2 you will drop the fg lower by adding fermentables. Malto dextrin will help give the beer body if that's what you want. I would just let it ride.

odedald

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Thanks for your answer.
About 1. can you expand a bit?
2. If i let the 1st fermentation go for like 3 weeks instead of botteling after 2 weeks or when i get to my wanted FG, will i still be able to get a similar final product like after a normal 2 week fermentation? If yes than what action do i have to take?

RM-MN

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1. I ferment small batches in big fermenters quite regularly. No problems.
2. Yeast eat as much of the sugars in the wort as they can. You have no control over this. It doesn't matter if you leave it fermenting 2 weeks or 2 months, when the yeast decide it is done, it's done and the FG is the FG.
3. You only control the FG by the mix of grains and extract and your choice of yeast.

odedald

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Great thanks a lot for the answers, very helpful

sidepart

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Not to speak for the guy, but during the fermentation process oxygen is pushed out of the headspace in your fermentation vessel by CO2 (given off by the fermentation). So basically that headspace is then filled with CO2.

I think his thoughts are that with such a large fermentation vessel, you might not be filling up the entire headspace with CO2 thereby leaving some oxygen that could oxidize the beer.

I don't really agree. During primary there's so much activity going on, I feel like your 15L of headspace will most certainly fill up with CO2. Of course I don't really have any scientific proof to give you on this, and I'll probably be corrected if I'm wrong.

Maybe if you were using that vessel for secondary though, that might be a problem.

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Obliviousbrew

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I have a a 60l fermentor that a lot of times i use as my primary, with an ongoing fermentation there is not an actual risk of oxidizing the beer, if you are not going to secondary there is a chance that you oxidize the beer, in my case if I don´t want to transfer this is what I do: I ferment on the lower side of the strain most of the time, after about a week 98% of times FG is reached and krausen falls and airlock stops bubling, i take out the fermentor out of the chamber I change the airlock for a stopper (it´s really easy with my speidel fermenter) as beer gets warmer co2 is driven out of the solution filling the headspace after a few hours y loosen the cap some co2 escapes and close it back again. Never had a problem with oxidize beer.

JesperX

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For a primary you shouldn't have any issues- the yeast will generate a nice blanket of C02. I wouldn't do a secondary with that much headspace though.

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beaksnbeer

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Number of weeks is not as important as FG. reading. 3 weeks is not that long for full fermentation, depending on OG.

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Guerrilla

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Yes as has been said you will be fine with the large fermenter for primary because of the CO2 blanket and the fact that the yeast provide a surface barrier during early fermentation then they work as reducers (opposite of an oxidizer) while they are still in suspension, aka until you are carbonating the beer, anyway. People worry a lot more about oxidation than they should, unless you are going to be bulk aging for something on the scale of many months/years and not weeks, the yeast are going to protect their beer! Just dont go shaking the fermenter violently everyday and you will be good.