Slow Fermentation at Low Temperatures

I brewed my first AG batch last weekend. I made a 2000ml yeast starter with 1 vial of WLP001. I used 13lbs 2-row, .5lbs crystal 40:, .5lbs white wheat and .5lbs carapils. I brewed outside, cooled the wort to 62 degrees, aerated the wort, and pitched the yeast into the carboy. There was still some yeast cake at the bottom the flask so I dumped a bit of wort in, shook it around and put it in the fermenter. I put the fermenter into a chest freezer I bought for fermentation. I left the fermenter in the chest freezer overnight with the temp controller set to 65 degrees. I don't know if it got warm enough in my house to bring the fermenter up to temperature so I put a pan of just-boiled water into the freezer to try to bring the temperature up. Now the fermenter is at room temperature, about 65 degrees. There is a nice layer of krausen on the surface of the beer but the airlock of bubbling VERY slowly. In the past I've used US-05 and fermented at warmer temps and the airlock went crazy. Is the slow fermentation simply due to the colder temperatures? Should I do something to get it going faster? Should I pitch another vial to be sure I get good attenuation? Any assistance would be greatly appreciated. Thanks!

Nice layer of Krausen sounds good to me. Let it sit at 65F. There really isn't any need to pitch more yeast. Last time I fermented with that strain at 65F, with a starter, it took 9 days to reach final gravity. Stop fluctuating the temps and let it stabilize at 65F.

Slow and steady fermentation is good.

You'll get a cleaner tasting beer with fewer esters and less chance of fusels.

My brewshop hovers at 60-62 this time of year so this is when brew like crazy...stock up and get all 20 kegs filled.

Once summer gets here and my shop gets to that 76-78 range...then it's on to the Belgians.