Carboy Size: Single Vessel Fermentation

So as some have suggested on this forum, I do my entire fermentation in one carboy. No secondary. My question is, for this style brewing, what is the ideal size carboy?

the 6 and 1/2 gallon ones work good for that. course they're really heavy. i used to use em. but switched back to a 7g bucket.

6 gallon better bottle here

Typically, you'll want to have an additional 1-2G of head space on your vessel, for the krausen. If you used a 5G vessel for 5G batches, you'd lose volume every time to blowoff.

I choose what carboy I'll use based on what beer I'm brewing:

A big beer? Better use a big carboy.
A small beer? Better just shoot for 6 gallons and use a big carboy.

Just a thought..peak at our site if you will...we have 7 gallon stainless steel carboys we call Cavern's. Thanks

DeepWoodBrew said:

Just a thought..peak at our site if you will...we have 7 gallon stainless steel carboys we call Cavern's. Thanks

Click to expand...

Not to knock your product, but I just can't justify SS being worth ten times more than a bucket. Not to mention that because of the dimensions the temp difference from the sides of the cavern to the center, would be bigger than in a bucket.

I could see it being nice for aging wine.

Although It would definitely be more appealing if you had a lid with a cooling system. Maybe not a refrigerant filled helix with a pump and condenser, but even a spot for an ice pack to fit down in the center of the wort would be a significant advantage to homebrewers.

Edit: Sorry, double post.

I use 6.5 gallon carboys and have only had the kreusen invade the blowoff tube once on 12 batches. Too much headspace in this to use it as a secondary IMO.

So it sounds like 6-6.5 gallons is ideal. My question is, would that volume be too much head space to keep the beer in for the entire process? (Keep in mind I'm using no secondary. I leave in primary for 4 weeks then bottle.)

JustinMaster said:

So it sounds like 6-6.5 gallons is ideal. My question is, would that volume be too much head space to keep the beer in for the entire process? (Keep in mind I'm using no secondary. I leave in primary for 4 weeks then bottle.)

Click to expand...

I leave mine in for 3 weeks minimum...usually 4. The CO2 pushes out all of the Oxygen during fermentation. As long as you have the airlock on there with liquid in it (I use vodka or sanitizer), no problems.

Like I said, too much headspace to use as a secondary. I use a 5 gallon carboy when I do a secondary.

(The one on the right is less than 5 gallons...it was my friend's first home brew on my equipment and he did not want to top off the boil kettle to get to 5 gallons). Mine also came in a little shy after siphoning off wort.)

Not at all, I sometimes use a 7.9 gallon bucket for the entire process. The head space doesn't actually matter too much, your yeast will be producing enough co2 to displace all of the oxygen from the head space in just about any vessel.

Just to clarify, I understand the c02 pushes out the oxygen during fermentation. But once fermentation is complete, and you start to open the vessel to take samples, replace blowoff, ect., isn't oxygen let into the vessel?

JustinMaster said:

Just to clarify, I understand the c02 pushes out the oxygen during fermentation. But once fermentation is complete, and you start to open the vessel to take samples, replace blowoff, ect., isn't oxygen let into the vessel?

Click to expand...

CO2 is heavier and will stay in the fermenter. Even if some oxygen got in, the CO2 forms a protective blanket over the beer.

Well, CO2 is heavier, but gasses don't quite function that way. If you're opening the top to take samples, yes, you're introducing oxygen back into the fermenter, back into contact with the wort/beer, and--if fermentation is complete--then it will start to go back into solution in the beer. If the beer is still fermenting, than the beer is probably at or near maximum dissolved gasses and will not take up any O2, especially if the beer is still putting off a little CO2. If you take the lid off to sample it and you've been fermenting at 60-63F, then after you replace the lid (assuming fermentation is complete), you can raise the temp or *carefully* transport the carboy to a warmer area of your house for a diacetyl rest at 68-70F to complete. The warmer temperature will actually cause some of the dissolved CO2 to come out of solution (liquids hold less gas as they warm up and expand), replacing what was lost and helping to force introduced O2 back out of the carboy.