5 Gallons in 6.5 Gallon Carboy

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Morkin

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Hello again to my brewing brethern.

I intend on brewing a blonde ale all grain this evening. I have recently been given 4 carboys, and have been busy filling them. However, I am in a little pickle.

The only carboy I have left is a 6.5 gallon glass carboy, and I intend on putting 5.5 into the carboy to ferment. I have read somewhere that this could potentially cause a problem. I do have a 6 gallon carboy, but it is fully of delicious Apfelwein, and I really don't want to rack it to a 5 gallon carboy.

Is it really going to be a problem to use a bigger carboy that has some head space? Thanks for all opinions and comments you may have.
 
You'll be fine. Actually, you may even not have enough headroom if you're putting 5.5 gallons in the 6.5 gallon carboy. Be prepared to have a blow-off rig set up if the krausen gets too close to the top. Otherwise, you'll be fine. Most people use 6.5 gallon carboys or buckets for primary fermenters.
 
Right now I am trying to 2.5 gallon batch in a 5 gallon carboy. I have been scouring the forums for reasons not too and the general consensus is that so long as your not letting the beer sit there for several months, oxidization should not be an issue in the primary, though it can be with the secondary. I think you will be okay!
 
Yooper has it. With one of my brews, I had <5 gallons in a 6.5 gallon carboy and the krausen came up through the top of my airlock.
 
It will actually be a little less. I am boiling 6.5 (roughly) for an hour, so I should get 5.5 with about 5.25 actually going into the fermenter when I factor in Cold Break loss. Thanks guys, my worries are gone.
 
Plus, while the yeasties are fermenting, they're blowing off CO2 - displacing the O2 in the headspace. Within very little time, it's nothing but a thick layer of CO2 sitting on top of your beer. So no worries, 2.5 in a 5, 5 in a 6.5 - it's all good!
 
Actually, you may even not have enough headroom if you're putting 5.5 gallons in the 6.5 gallon carboy. Be prepared to have a blow-off rig set up if the krausen gets too close to the top. .

You shouldn't ever doubt Yooper.....

I actually don't own a blow-off tube which has never been a problem in the past. HOWEVER, I brewed on Saturday and went downstairs yesterday to check on the brew. I noticed that I was close to the top with Krausen bubbles, but thought nothing of it.

This morning, my airlock was almost full of yeasties and krausen. I quickly though of ways to create a blow-off system. This is what I did.

I installed an old airlock without the movable plastic peice and the top. I attached a 9/16th tube to the inside of the airlock and put the other end in an old milkjug type gallon jug with water. I then attched the airlock to a stopper and put back on my carboy.

If I hadn't been in a rush to work, I could have devised something better. Do you think I"ll be ok with this? In my haste, I did not sanitize the jug or the tubing, but did sanitize the airlock. SHould be ok, as it was fermenting for about 2 days before I did this. Never had this much bubbles and Krausen before!!!
 
I use 1" ID 1 1/4" OD tubing. It fits perfectly in the neck of 5 gallon and 6.5 gallon carboys. With this setup you don't have to worry about the blowoff getting clogged and causing a huge mess.
 
I used to use a 1" tube. However, I found it to be stiff and in a near-permanent curve, making it sometimes difficult to keep the end submerged. Also, if you get krausen in the tube, it is a pain to clean. For about the same price as 3' of tubing, I constructed a blow-off with PVC. See here: https://www.homebrewtalk.com/f51/cpvc-blow-off-129082/ (entry by Blender).

Easy to handle, easy to clean.
 
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