Blow Off Tube

[mcurtis431]

What is everyone's best method for using a blow off tube with a bung type thermowell? Brewed a stout (OG 1.06) over the weekend and fitted with my new thermowell and new stainless steel blow off tube. Woke up the next morning to this. Obviously a lot of krausen, but I thought by using a blow off tube I was in good shape. I don't think the bung was tight enough in the carboy neck and that is why it is coming out the top. I pressed it down further, but now I am getting krausen out the blow off tube and it is making a complete mess in my fermentation chamber.

 

[Pappers_]

You want to get krausen out your blowoff tube, if by that you mean the krausen is going through your blowoff tube and into the blowoff jar. That's the point of it - when you have so much wild krausen activity, instead of pushing through your airlock, it goes through the blowoff tube and gets captured in your jar. If its overflowing your jar, use something bigger. I use a small, 1 gallon bucket, fwiw.

If you mean the krausen is coming out around your blowoff tube in the thermowell bung, then that means the blowoff tube isn't tight enough in the bung, but I'm not sure what you can do about that.

 

[IslandLizard]

You really should leave more headspace, 1/5-1/4 of the wort/beer volume is recommended. Some beers and yeasts can do fine with less, others need more. Ferm temps are also a factor.

The CO2/foam/krausen will find a way to get out. If more is generated than being flushed out pressure will build and something's gonna give. Hopefully it's the bung shooting out... Don't restrict it.

That "blow off" tube (looks like 3/8" OD/ 5/16" ID) would be fine to release the gas, by itself, but may be a bit too tight to push out larger amounts of thick, sticky krausen. Many of us use 1/2" vinyl tubing on top of a 3-piece airlock stem. Some use larger diameters, as much as 1".

If you want to keep this setup, siphon 3/4 gallon of beer out into a gallon wine jug and ferment that in there. The yeast is in there already, no need to repitch any. That will leave a gallon of headspace in your large carboy, which should be enough, but keep an eye on it.

 

[day_trippr]

Ditch the thermowell and go with 1" ID/1-1/4" OD tubing stuffed straight down the mouth of that carboy.
Strap the bare probe to the side of the carboy with some inch-thick closed cell foam over it and even that over-filled carboy will work it out

Cheers!

 

[jhnmdahl]

The problem is that your blowoff tube isn't big enough to carry blowoff without clogging. Day Trippr's advice to use a larger tube stuck directly into the carboy is the most effective solution, and looks something like the attached photo (one end stuck firmly and directly into the carboy, and the other end underwater in a container of sanitizer solution).

Also, many kits come with a five gallon carboy and a six gallon carboy - you'll have fewer problems with your five gallon batches if you use the six gallon carboy for primary fermentation.

 

[robbeh]

You really should leave more headspace, 1/5-1/4 of the wort/beer volume is recommended. Some beers and yeasts can do fine with less, others need more.

I know almost all brewing is a matter of opinion/testing things out yourself but is there a source for this? I thought the only issue with headspace is it can get messy if you have too little and that it only mattered in bottles for O2...

To stay on topic though, the issue is your bung not sealing well enough. You blow off tube MIGHT also be too small. I usually tape my bung down with box tape. day triper is also got a good solution there.

 

[IslandLizard]

I know almost all brewing is a matter of opinion/testing things out yourself but is there a source for this?

Mostly common sense.
That headspace recommendation applies to primary fermenters. See the example above what happens if you have far less. With a small headspace, when a blow off tube is used, beer and krausen will blow off into a collection container and is wasted. You'll end up with less beer. You may as well not fill that fermenter as high.

Secondaries, if there's reason to use one at all, should have very little or no headspace (1" under the bung).

I thought the only issue with headspace is it can get messy if you have too little and that it only mattered in bottles for O2...

It sure can get messy, see what's happening already. If that blow off tube clogs up the bung will be pushed or blown out. When the bung is taped or tied down, something is going to give... pressure is building... needs to go somewhere...

Bottles need the right amount of headspace, usually the amount the bottle filler leaves behind when pulled out after filling.

 

[robbeh]

Mostly common sense.
That headspace recommendation applies to primary fermenters. See the example above what happens if you have far less. With a small headspace, when a blow off tube is used, beer and krausen will blow off into a collection container and is wasted. You'll end up with less beer. You may as well not fill that fermenter as high.

Right, that makes sense and honestly even if it's a little, it's still waste. I have had some vigorous fermentation with tight headspace and even with a lot of blowoff, I maybe lost 1 beer. But 1 beer is 1 beer .

I was worried there was a different reason, like some reaction with less headspace that caused off flavours.

 

[ncbrewer]

I was never comfortable with the cleanliness of a blow-off tube - I understand I'm in the minority. Several years ago I started using a 7.9 gallon bucket for 5 gallon batches and haven't had any problems - no blow-off tube.

Another "fix" that I used previously - a 6.5 gallon bucket with the lid loose, and about a one-pound weight on top. After a few days, I snapped the lid on.

 

[jjw5015]

It's just not enough space