Looks like this thread is already deviating a little off-topic, but just thought I'd chime in: After having my 5th batch push through the airlock like three times (I kept thinking it was done kraeusening!) I have determined that I just can't freakin' tell which batches are going to need a blowoff hose and which aren't. Since it doesn't hurt a damn thing to use one, I've instituted a policy of always using one for the first few days regardless of gravity, yeast, headspace, etc. Even in my first half-dozen batches, I've had ones that I was certain would blowoff not, and ones that I was certain wouldn't go shooting out through the airlock. Yeast are capricious little pranksters, better not to second guess them.