I used a different yeast than normal for my CDA based on cost and availability. It was very active with a huge krausen and I could watch the convection through the carboy, so I'm not worried about the fermentation per se, but after the krausen died down, there's still a huge mass floating on top, which pretty much looks like yeast, and I'm wondering if this is normal for this strain. Imperial Independence is tabbed as Anchor Liberty.

Apologies for the crappy cell phone picture. My main concern is that I plan on dry hopping this beer in a few days and worry that the pellets will just float on top of this float and not break through to the beer below. I've had some wicked krausen rings before, but not anything that hung around this long.
This is two weeks into fermentation.