richbrostrom

Recipes 

Is it just preference, or does the blow off tube handle a "more active fermentation?"

Sorry if this has been previously discussed to death.

BlindLemonLars

Recipes 

A blow-off tube is always a good idea if your fermenter doesn't have a lot of headspace, if you're using a really active yeast strain (like a Hefe) or brewing a really big beer. There is no reason you can't use one for every beer though, which is what a lot of people do.

Personally I like the convenience of an airlock, and since I use ferm-cap drops in my boil I've never had a blow-off problem...until my last batch of APA! I checked in on it two days after pitching to find it had blown it's stack, flooded my fermentation freezer with krausen and decorated the lid. While I spent the afternoon cleaning and disinfecting my freezer, I did a lot of thinking about blow-off tubes.

OTOH, maybe I'll just start adding ferm-cap directly into the fermenter as well.

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FERMENTING: Members Only Maibock, Apfelwein
KEGGED / BOTTLED: Düsseldorf Altbier, Honeydripper Hefe, High Yellow Strong Belgian Ale, Irish Red Ale, Canned Heat Wee Heavy
ON TAP: Ó Flannagáin Extra Stout, Squeeze My Lemon Summer Blonde, Apfelwein
ON DECK: Munich Helles, Ó Flannagáin Extra Stout, Cold Shot ESB

blowmax10

Recipes 

in my experience, the only time you need a blow off is if the foam goes up too much and is going to over flow

Me, I use the three piece and have a blow off ready if I need it - but I've only had one batch that I needed it and never in my 6.5 gallon carboy

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The Joplin Homebrew club

CHansen6

Recipes 

The blow off tube handles more active fermentation. It allows any high krausen to spill out the top and into the bucket/glass/growler that you have the tube in. An airlock doesn't allow as much spill over, and can result in the stopper/lid popping out.

llazy_llama

Recipes 

My advice to all brewers is to always use a blowoff tube in the following situations:

1. You're brewing a new recipe that you haven't brewed before
2. Your fermenter hold less than 6.5 gallons (assuming a 5 gallon batch)
3. You are using a notoriously active yeast strain. Like BlindLemonLars pointed out, hefe yeasts are a prime example
4. You're brewing a big beer. In this case, anything over 1.060 OG
5. You're pitching onto a yeast cake

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flyangler18

Recipes 

Don't fear it.

llazy_llama

Recipes 

Oh yeah, that works too. It's not just for kitty hats anymore!

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DrinksWellWithOthers

Recipes 

I use 3 piece airlocks and usually use FermcapS. If fermentation gets out of control I can take the bubbler part out of the airlock and stick a piece of 5/8" tubing on.