When to use a blowoff?

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Nov 25, 2007
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How do you know it is necessary to use a blowoff? I assume you are safer to use one when brewing higher gravity beers, but are there any guidelines to using one? Plus, I have a 6 gallon ale pail, so can one be used with this type of bucket?
Always!!!!! I always use one just in case. It is easy to do, and the short answer is that you don't know that you need one until you have krausen all over the floor (or worse).

Typically, if you are pitching a huge starter or if your fermenter is really full you will need one.

Better safe than sorry.
I have an Alpha King clone in my primary bucket right now that is fermenting pretty heavily. Had it going with just an airlock but it kept foaming into the airlock and clogging it up. After changing the airlock three times yesterday thinking it would subside I just ran a little plastic tubing that fit right into the gromit/hole in the lid. I'm not sure what the measurement is on that piece of tubing though. Or you can take the gromit out and fit some tubing in the hole that way.
I had pretty good fermentation with a stout that I brewed. Krausen was coming up into the airlock, and around the gasket on the bucket lid. I didnt know what was going on at the time, so I asked on here, and was advised to use a blow off. I've used one every time since then. Better safe than sorry. And the AlePail will work just fine, thats what I use.
Six gallons is cutting it a bit close. I'd say once you're over 1.050, be safe.

A lot will also depend on the yeast. If you use a Belgian Wit yeast, use a blow off...regardless.
I brew 5 gallons in 6 gallon Better Bottles and I only use them when I'm going a beer that has wheat in it. thus far my Blue Moon clone and my hefe have needed them, the rest are just fine without.

Of course, I also know I'm tempting fate. If you are following "best practices" ever brew should get one.
I think I'll go ahead and start using one for future batches. I just checked to see if my bottling tubing would fit in the Ale Pail lid and it does. (thanks! jvh261) Does the end of the tube need to be immersed in anything or just open to air?