strange. i'm usually just double-pitching activator smack packs with yeast fuel added with 15 left in the boil - oxygenated with drill-mounted whip. ferment takes off in 4 or 5 hours, vigorous for a few days, usually 90% done after a week or sometimes a little less. temps kept around 60-62* through entire primary. transferred to secondary when krausen has fallen and no visible signs of ferment exist (though airlock may still bubble ocassionally, 1-3 times per hour)... even with vigorous ferments, no blowoff. ive had the double-bend airlock bubbling like a machine gun at times, but krausen never gets more than a few inches high, well below the neck of the BB. this is in a 6 gal BB making a 5gal+ batch. little more than 5gal, 5.25 max.