To Blow-off or not to Blow-off?

I'm not exactly a newbie but I'm still in the novice phases here... I've always brewed 5-gallon batches from kits or CloneBrew recipes and I've NEVER used a blow-off tube because I didn't know they existed until recently--I've always just use an airlock. I guess I've just been very lucky that I've never had a leak or explosion.

The question is, how do you predict *in advance* whether you will need to blow off? As in, *before* the mess? Are there certain kinds of yeasts or combinations of ingredients that build up more pressure than an airlock can handle?

My fermenting "closet" only has a vinyl accordion door so if I had a leak or popped lid I would not only be cleaning up wort, but also two alcohol-poisoned cat corpses (or at the very least, cat vomit in every room of the house).

Thanks,
chris.

P.S. I do my primary fermenting in an a plastic bucket, secondary in a glass carboy.

Really it has a lot to do with your gravity, temperature and type of yeast. I used to only use airlocks, but here lately I will NOT trust a beer without a blow off. The last 3 batches I have made all blew atleast a few cups out of a 7 gal carboy. Just goes to show that you should never trust your beer to murphy. There's a law for that.

I typically stick to the same 6 yeast strains and unless I'm reusing a cake I just know that they're not gonig to go crazy on me and require a blowoff.

By the same token, when I brew a Hefe I don't even get an airlock out. Blowoff tube just automatically goes in.

I just always use a blow off for the first couple days. Its easy and may potentially save a huge mess. If you do 5gal batches in 7.9gal (or bigger) fermenters then the blowoff is probably not necessary but for normal 5.5gal in 6.5gal buckets or 6gal carboys why take the chance?
Craig

I use a large (7.5 gallon) plastic primary bucket. I've used a blow off tube maybe a total of three times. But, I don't make hefe's or other wheat beers that are notorious for blowing their tops. The last time I used one, I knew it was coming. I pitched on a yeast cake and waited. After it got started, I left the blow off tube on until it subsided a few days later. Otherwise, I don't use them.

I have a 6.5 gallon bucket and 7 gallon carboy that are my primary fermenters so I don't use blow off tubes. If I was using 5 gallon carboys I would. Actually I came close to blowing up the 6.5 bucket when I used the yeast cake from a prior batch. I don't play that game anymore.

I've always used a blowoff tube and have never had to clean up a beer guiser. As a result, I will continue to use a blowoff tube to be safe. Setting up the blowoff tube will ALWAYS be easier than cleaning up beer.