So I just recently experienced my first blow off. My only question is how likely am I to experience it again with this same batch during fermentation? I'm a day into the primary fermentation period. Doing a Hefeweizen all-grain recipe using Wyeast weihenstephan #3068. I'm using a standard bucket with a sealed lid and airlock.
If the blowoff has settled down (i.e. nothing solid/liquid is pushing up through the airlock), you may well not see it again with this batch. I know 3068 has a reputation for very active fermentation, but I have used it many times and found it to really not be all that crazy with a low gravity wort (like a hefe), assuming adequate headspace and controlled fermentation temperature. I assume this is a 5-gallon batch in a 6.5 gallon bucket. What was the temperature of your wort when it was blowing off? (Not ambient temp, but the actual wort.) Also, there's no harm in using a blowoff tube instead of an airlock if you're concerned.
I didn't measure the temp when it was going crazy. I don't own a blow off tube or anything like that so I was totally unprepared for it. I just used my siphoning tube and stuck it in the lid hole. Is there a greater risk of contamination now? It's been almost 12 hours now and the inside of the tube is pretty well caked in crusted foam.
As long as you sanitized the tube, it should be fine. You should also put the other end of the tube in a container of water (or better...starsan solution), so that the blowoff also functions as an airlock. Google blowoff tube or blowoff hose for about a million how-to's. ETA: even if you didn't sanitize the blowoff tube, you're probably fine. But slightly less certain.
To answer your first question: expect one, and only one, high krausen. Here's what's going on in your fermentor: In a bucket you don't know where you are . . . when you notice blow-off you could be climbing the curve, peaking, or on the down side. But barring something extreme like large temp swings you will only get one "top of the krausen curve". Congratulate yourself on robust fermentation and enjoy the aroma.
