7.9 gallon primary to big?

[ebid]

I know 6.5 is ideal but I ahve a 7.9 sitting around and am wondering if that is good to use for the primary

 

[ThirdGen]

My primary is 8 gallons and from what everyone told me here, it's fine since your CO2 will cover the head space. Secondary is a different issue though, you should have the secondary have as little head space as possible I believe.

 

[bknifefight]

It'll work just fine. I will often do 2.5 or 3 gallon batches in a 5 gallon carboy. Like ThirdGen says, the CO2 will force and O2 out and keep it from getting oxydized.

 

[Justibone]

Headspace is indeed the issue. In primary its not a big deal but in secondary (if you use one) it is. If you have access to CO2 then you can put a layer of it into your secondary -- enough of a volume to drive out any room air -- and still use too big of a container for a small batch. It is a risky way to do secondary, though, and kind-of sloppy, because gases are essentially just extremely non-dense liquids, and so they don't move around in an orderly fashion.

 

[BioBeing]

Make more beer! Seriously - shoot for ~6.5 gallons to the 7.9 gal primary.

 

[springer]

I use a 15 gallon Dulex for my 10.5 gallon brews never had a problem. A lot more headspace than you have.

 

[Justibone]

I use a 15 gallon Dulex for my 10.5 gallon brews never had a problem. A lot more headspace than you have.

Edit: Extra headspace is a concern for secondary, not so much for primary.

I believe that the biomass of the yeast at work is more relevant to the percentage headspace than the actual, nominal volumes involved (i.e., 5 extra gallons of headspace is totally fine in a 50 gal fermentor but 5 gallons headspace would be a significant problem in a 6.5 gallon fermentor).

I also believe that you can try anything and pretty much get away with it when you are starting out. Later on, when you progress in your skills, you may decide to cut down on your headspace and notice a difference in your brews... but just starting out it is not the biggest deal.

The biggest deal is just *starting*. That's the first and tallest hurdle.

 

[springer]

I believe that the biomass of the yeast at work is more relevant to the percentage headspace than the actual, nominal volumes involved (i.e., 5 extra gallons of headspace is totally fine in a 50 gal fermentor but 5 gallons headspace would be a significant problem in a 6.5 gallon fermentor).

I also believe that you can try anything and pretty much get away with it when you are starting out. Later on, when you progress in your skills, you may decide to cut down on your headspace and notice a difference in your brews... but just starting out it is not the biggest deal.

The biggest deal is just *starting*. That's the first and tallest hurdle.

Dude I am not starting out or are you talking the OP. And an extra 1.4 gallon headspace is not going to effect a 5.5 gallon brew . While I wouldn't go putting a 5.5 gallon brew in the 15 gallon fermenter he will be fine with what he has

 

[Justibone]

Dude I am not starting out or are you talking the OP. And an extra 1.4 gallon headspace is not going to effect a 5.5 gallon brew . While I wouldn't go putting a 5.5 gallon brew in the 15 gallon fermenter he will be fine with what he has

Of course you aren't starting out! You've been at this a lot longer than many have, I'd wager. This is, however, the "beginner's" area. My information is beyond redundant for you -- I'd bet you know a danged sight more than I do. My information is to encourage people who are new to just start with whatever they have or they can get cheaply.

You are totally absolutely correct that 1.4 gal of air won't affect 5 gal of liquid... IN PRIMARY. It won't matter at all unless there is a secondary fermentation required. {Back of envelope calculations.} In secondary 1.4 gal of extra air is about 20% O2, which means around .3 gal of air... ~1.1 L of oxygen. At 32 g/mol and 22.3 L/mol, that's .05 moles of oxygen, which in 5 gal (~19 L) ends up at about 2 mM of nasty taste. Brew-noobs might not taste that amount of unpleasantness from side reactions, but old hands probably would. That's my point.

And you know that already, so its not directed to you, but to the newbs like myself and others in this forum.

Cheers!

 

[springer]

ya I wouldn't do that with secondary mainly because I don't secondary

The OP was asking about primary so we have no idea what he his process is for secondary

 

[Justibone]

Edited above post to clarify.

 

[wzup97]

Like BioBeing said "Make more beer". I only use the 7.9 buckets. I can make larger batches (6 - 6.25g) and there is less chance of a blowoff. Never a problem even with 5g batches.

 

[Yooper]

I use a 7.9 gallon "ale pail" for primary of 5-5.5 gallon batches. I always have, and I expect I always will. It's actually the perfect size- plenty of headspace so that I've only had a blow off ONCE in all of my brewing time. It works great for me, and I'd recommend that for anyone!