Two Carboys Fermenting ... Two Questions

I'm currently brewing two beers and am seeing some interesting ferments:

Carboy 1 is a standard pale ale I've brewed dozens of times. I'm using Wyeast 1332 - Northwest Ale for the first time (I normally brew pales with US-05). The beer fermented great for a week, but the krausen head never subsided (as is normal with the US-O5). I was planning on racking and dryhopping today, so last night I GENTLY rocked the carboy and the krausen/foam instantly collapsed back into the beer -- I figured it was just laced foam left over. Well, today after work, I checked and it looks like it went through another ferment -- fresh krausen! Any ideas why I would see additional fermentation activity after a week?

Carboy 2 is a standard wheat, but fermented with White Labs 320 -- American Hefeweizen (first time with a Hef). I brewed this beer on Sunday and it went through a violent ferment (blow off tube spewing foam). Well, I checked after work today and saw no airlock/blow off activity, krausen is still high. Fearing the blow off was clogged, I checked for blockages and there were none. I'm guessing most of the primary is wrapping up. Has anyone seen a beer finish primary fermentation that fast?

For the record, both beers are in six-gallon glass carboys in a fermentation chamber set to 65. I plan to let both condition a bit before kegging.

 

I brewed up my first hefe a few months ago with wlp320. For what its worth it was a quick, violent fermentation... Lots of blowoff activity for 2 days and then nothing much for a couple weeks. Mine attenuated down to 1.015 in 15 days.

 

Fermentations are all different. I've seen high krausen, low krausen. Krausen that never falls, krausen that falls after a day. I've even seen krausen with krausen on it.

I'd say with the first carboy, fermentation was never completely finished...which might have been why the krausen never fell. Hydro readings would have told you it was done...but if you didn't take them, I would just assume it had never completely finished. Most likely when you shook it, it bumped up the activity a notch.

The second one is probably just finishing up. I've had batches almost finish completely in less than 48 hours.

 

Rocking the carboy roused the yeast got better attenuation

Wlp380 finished my wheat in less than 30hrs

Clem

 

I have had a few brews where it seemed like the krausen just did not want to fall. My most recent was a wit that i used the wyeast belgian wit 3944 and it has been in the primary for over 3 weeks and the krausen still has not fallin back in. Gravity readings show its done just need some time to keg it. Also i had a few oatmeal stouts, IIPA, kolsch and a few others have the same issue with the krausen taking forever to fall back in. But even with the krausen on top, gravity readings showed they were done and all turned out great. Also, i have had some of them eventually fall back in hitting the 3-4 week mark while i tried to find time to bottle/keg the beer.

Also i always use wyeast strains on my beers for what its worth. Usually maintain a steady fermentation temp in the basement usually mid range for the yeast.