Carboy Size

I was at my LHBS the other day, purchasing a new better bottle(they don't sell glass carboys, I am brewing tuesday) and I was talking to the guy who has been in there every time I was in there. I asked him a question, don't quite remember what it was, but his response, albeit off topic, irked me.

shopkeep: That's not a fermenter, at least not for beer.
me: Huh?
shopkeep: For a five gallon batch?
me: Yeah.
shopkeep: Your seal will blow right off.

Now this conversation puzzled me. I know that this person is more of a wine guy. The store is more oriented towards wine, so I don't want to take his advice to heart, being that I do not believe him to be an expert.
I then went on to ask him about using a blowoff tube. He said it wouldn't make a difference, and that I needed about 6 inches of headspace.

The batch I am brewing on tuesday will be only my third. My second was not a full five gallon batch, and my first, I left room because I had no idea what I was doing, and I ended up with 37 beers instead of the full 48.

Should I be using a 6 gallon carboy for my 5 gallon batches? Can I get away with just using a blowoff tube?

I would use the 6 gallon carboy AND a blowoff tube.

Better Bottles are great, but you need the 6-gallon one for fermentation, or you'll be blowing off much of your yeast and some of the beer as well. If you only have a 5-gallon, I'd stick to 4-gallon batches.

I can't answer for the 5-gal better bottles (I don't own any and the actual liquid capacity could vary between better bottles and glass carboys) but I do use 5-gal glass carboys with a blowoff tube on a regular basis with my 5-gal batches.

I do usually get some blowoff when using the 5-gal carboys so definitely use a blowoff tube. So far this has worked very well for me. The beers have turned out great and there haven't been any negative side-effects for me yet.

What have you been using as a primary?

I don't know that it will necessarily "blow right off" but it could. I think most of us use 6 gallon carboys or 6.5 gallon buckets for "primary" fermentation. You are usually gonna lose quite a bit of beer to trub and all that, so if you ferment in a 5 gallon container, you're only going to get 4 or so gallons of beer or a bit more. By fermenting in the slightly larger vessel, you can either rack the 5.something gallons of beer into a secondary conditioning vessel or into your bottles or kegs or whatever you want to do.
That said, if you don't care about having a 5 gallon batch and are okay with less, then there is nothing inherently wrong with using the smaller cowboy, you'd just need to scale your recipe accordingly. Hope this was helpful.

I've looked into this as well as I also just recently bought a 5-gallon plastic carboy. The general consensus seems to be that a 5 gallon batch in there is guaranteed to overflow and you'll easily lose a gallon from blow-off. If you fill it up with water you can see how much space it'll take up, aka. almost all of it. You'll have maybe a couple of inches of head space.

I'm going to be making 16L batches in mine. Should give it enough space.

alenub said:

What have you been using as a primary?

Click to expand...

I have been using a 5 gallon BB for my primary. My other one is currently lagering in a fridge and my first one is warped to the point of holding about 4 gallons at most(that'll learn me to put hot wort into a carboy)

so the consensus seems to be to brew smaller, which I have no problem doing. If I use .5-1 gallon less, how much less priming sugar should I use when I bottle? I am assuming about an ounce less would be appropriate. I think that bottle bombs would be even worse than a carboy bomb.

ghank15 said:

I have been using a 5 gallon BB for my primary. My other one is currently lagering in a fridge and my first one is warped to the point of holding about 4 gallons at most(that'll learn me to put hot wort into a carboy)

so the consensus seems to be to brew smaller, which I have no problem doing. If I use .5-1 gallon less, how much less priming sugar should I use when I bottle? I am assuming about an ounce less would be appropriate. I think that bottle bombs would be even worse than a carboy bomb.

Click to expand...

http://www.brewheads.com/priming.php
This calculator should work nicely.

One more thing. The actual volume of various bottles/buckets/carboys can, and usually do, vary from the advertised capacity. I did an quick experiment a while back and I think my 5-gal carboys held more like 6-gals, and the 6-gal carboy held something like 7-gals of water. I can't recall the exact figures but I do know that they held more than the advertised volumes. You can try this yourself by adding water in carefully measured increments, until the vessel is completely full, and see what you get.

I do use 6-gal carboys and 6.5 gal plastic buckets for primary fermentation most of the time... but I won't hesitate to use a 5-gal carboy either.

Just sayin'.

Get the 6 or 6.5 gallon carboy. I just put a batch into primary in my 5 gallon glass carboy for the first time yesterday and woke up this morning with it coming out of the airlock.

I don't think I will put a full 5 gallons in it again without a blowoff tube.

buy a bucket

Get the 6

6 works great jsut use blow off tubes

Seven said:

One more thing. The actual volume of various bottles/buckets/carboys can, and usually do, vary from the advertised capacity. I did an quick experiment a while back and I think my 5-gal carboys held more like 6-gals, and the 6-gal carboy held something like 7-gals of water. I can't recall the exact figures but I do know that they held more than the advertised volumes. You can try this yourself by adding water in carefully measured increments, until the vessel is completely full, and see what you get.

I do use 6-gal carboys and 6.5 gal plastic buckets for primary fermentation most of the time... but I won't hesitate to use a 5-gal carboy either.

Just sayin'.

Click to expand...

This is true, I just bought a 6.5 gallon carboy and when i measured the volume, 7 gallons fills it to the neck, no blowoff for me I guess