Blow-off When Fermenting in a Bucket

I’ve been brewing extract beers for a while, but brewed my first all-grain yesterday–Northern’s Cream Ale. I typically ferment in a 6.5 gallon bucket with an air lock. I filled the bucket a litte fuller than normal yesterday than I normally do when extract brewing–about 5.5-5.75 gallons. My OG was lower than the target Northern said I should hit–1.033 vs. 1.040. I’ve never had any issues with a blowoff when extract brewing which is why I’ve continued to use an air lock. When I went down and checked on it this morning, everything was fine and the air lock was bubbling away. When I went down and checked it a little while ago, I was suprised to see that I had my first blow off. From what I’ve heard and read, the beer will be fine as long as I keep swapping out the air lock with a clean and sanitized one?

Also, any guesses as to the cause of the blow off? I guess I thought this would have only been a problem with a higher gravity beer and not one with an OG of 1.033? Or am a wrong and the OG doesn’t really have anything to do with it? If it’s not the OG, I’m assuming the only other cause could have been the volume of wort that I filled the bucket with? Thanks for any help/suggestions!

Probably the combination of the more fermentable, fresher wort and the much fuller bucket. The extra volume is also why your OG was lower.

Ok. Yeah was borrowing a friends kettle yesterday because my new one didn’t show up yet, so I was kind of guessing at my final volume while boiling. My efficiency coming out of the mash tun was a little low too, which I’m sure didn’t help. All things to work on fixing next time…

I did swap out the air lock, and when I peeked inside through the grommet, the foam didn’t seem as high as what I would have expected. I’m thinking I might have also had my air lock pushed in a little further than normal too, which probably didn’t help matters either.

If you are using a 3 piece air lock, cut the “X” off the bottom of it. Then place some tubing on the post inside the air lock. Run this to a container of water.


I have 2 standard bubble air locks. Any reason why I couldn’t just cut off the bottom 1.5" of straight section off of one of them and put tubing over that and make a blow off hose? I have some spare tubing and it fits snug over the straight section.

And getting back to a question I had in my original post… I’m obviously an amateur when it comes to blow offs, but I’m assuming there shouldn’t really be any reason to worry that my beer is ruined? Thanks again.

You have an “S” style? Yes you could cut the bottom straight section off. I would hate to destroy an airlock like that.

A splice or elbow would work also. ... reId=10051