I think lenny is right here, no reason to risk something getting into the carboy when switching out a blowoff tube. And since the most brews aren't in primary for more than a week, it realy wouldn't matter much. As long as the end of the tube is submerged in some sanitizer solution or something (which you might need to change a few times if alot of gunk is getting blown off) there is no risk of anything getting into the fermenter through the tube. The only consideration I would see is that the longer all that hop gunk sits on the inside of the tube, the harder it is to clean off.lalenny said:I think that if you are going to set the blow-off tube up on your primary fermenter that you should just leave it on there until you are ready to rack to the second. I don't really see a reason to exchange the blow off tube for an airlock in the primary if the tube is already on there.
Majikcook said:If using a 6.5 glass carboy as a primary, when do you need a blow off system? Only on Big beers? Will a airlock do the job?
Janx said:I never use a blowoff tube. Use a big enough fermenter for the batch and you won't have a problem. Blowing off the krausen reduces hoppiness, head retention, etc. It's much better to not have to use one.
t1master said:glass glass glass!!!
i've not had a batch overflow yet in my six or six point five jugs. i make five gallon batches. the first batch with the irish ale yeast came really really close to the neck of the bigger carboy, but did not make it's way out. w00t!
...and then they blow out the blowoff with about 30% of the hop character...
Without a blowoff you get to keep the extra beers you put in there. It really is better to not have one if you can at all manage it (ie if your fermenter is large enough).