I am getting ready to brew a scottish ale 80/- in a 6.5 carboy. Would an airlock be alright or should go with the blow off tube? Also, is the tubing at lowe's or someplace like that the same as you would get from your LHBS? Thanks!
I use a blow-off for all of my primary fermentations. It's easy to do, and no risk of a wort explosion. Some people do them only for hefes and other higher-blowoff-risk beers.
Yes, any hardware store has tubing that will work. I like local stores over HD because you can buy it cut-to-length. Bring a carboy cap or rubber stopper with you to make sure you're getting the right diameter.
My last 6 or 7 batches have all started fermenting vigorously in under 2 hours after pitching. All of them have had significant blowoff. I usually just let it go and make a mess (the basement floor is vinyl tile and pretty easy to mop up) and then clean things up and replace the airlock 24 hours or so later when things subside.
But then about one month ago I had an epic blowoff event that made me change my thinking. I did my usual routine of pitching the yeast from the starter, oxygenating, etc. and then cleaned up the brewery area and went to bed. The next morning I woke up and went down to check on things and I noticed that I had a pretty big eruption and there was a LOT of beer on the floor. Instead of the airlock being near the carboy, it was nowhere to be found. There were tiny bits of trub scattered on EVERYTHING in the room. I mean EVERYTHING. The door to that room was open during the night and there were even bits of trub on the door to the room across the hallway. I'm guessing the stopper was in the carboy very tightly an a lot of pressure built up before it finally let go.
At any rate, I went out and got some large diameter blowoff tubing and used it on my last 2 batches. It's a bitch to clean the inside of the tubing but after that big "explosion" and the resulting mess I think it's worth it. Of course, I could also stop oxygenating, making starters, using yeast nutrient, etc. and I'd probably not have the rapid fermentations anymore, but I think despite the blowoff issues all those things make better beer so I'm inclined to keep doing what I'm doing.
My fermentations are good because I always us a starter from yeast that I propagate. I step up to the volume needed. I always use a blowoff any more because if not......... Boom. I keep my temps as low as I can for ales and they still ferment like crazy. Lager is a little less violent but still can come out the blowoff tube.
Umm, it has something to do with the bunge blowing off and putting krausen on my ceiling, wall, door, washer, dryer, etc... Pretty explosive and it can stop up the airlock or a small blowoff pretty easily.
Is there any flavor difference? Blowoff expells a lot of that stinky sludge that you see on the water line of your bucket or carboy. I used blowoff on my first batch and then thought it was unnecessary. I havent had good flavor since that 1st batch. I have only brewed like 5 batches in my life span.
I use blowoffs on my 6.5 carboys for the first couple of days, then switch out for airlocks when it calms down. Even some of my "calm" brews can go berserk without warning, so I do it for all of them. I just use 36" of 1" vinyl tube. To clean I wad up soapy wet paper towels and jam them in it and push through with a stick. rinsing is easy, sanitizing is easy, and filling an old gallon gatoraide jug with water for the other end is easy.
To answer the hefe question... well... hefe's are huffy. They like to blow off a ton of foam, probably from all the wheat in them, or maybe it's a quality of the yeast, but be warned!