Getting krausen but no fermentation

[hamaien]

This one seems to have stumped readers on another forum so I figured I'd ask here.

I brewed a Vienna lager last Sunday and pitched 2 packs of rehydrated 34/70 at about 48-49F. By Thursday the temp had risen to 50-51F and there were still no bubbles in the airlock so I opened it up and saw a big healthy looking krausen. Don't trust the airlock, right? So Sunday, one week from brew day, I still hadn't seen the airlock move. My paranoia got the better of me and I pulled a gravity sample. It hadn't dropped at all, still around 1.051, but the krausen was a good inch high.

The people on the other forum suggested that my reading was incorrect or I was not adjusting for temperature. The other suggestion was that the chunky bubbly foam on top of my beer was not actually krausen.

I tested these two hypotheses and here are the results: http://imgur.com/a/qGksk

Everything seems to be calibrated and that's definitely krausen on top of my beer. I brew 2-3 times a month so I'm fairly familiar with my equipment and I'm sure my original reading was correct.

Any ideas what's going on with my fermentation?

 

[FRS]

Weird! How does it taste? I'd leave it be for a few weeks and see what happens...

 

[flars]

You saw krausen so the yeast is beginning to do its' work. The yeast was pitched at a lower than normal temperature even for a cold pitch. Normal cold pitching results in a longer lag time. Give it 7 days before you start worrying. Hold the temperature 51° to 53°.
Until active fermentation begins.