The last beer that I did I used a bucket for my primary. The temp probe from a Johnson controller was taped to it and the temperatures were great (within 2 degrees).
I'm using a better bottle for a primary this time, and the temps are wildly fluctuating. The controller is set to 66 with differential of 2. The last I checked, the temp was showing 58 degrees. The probe is taped to the side of the better bottle and I have a single piece of bubble wrap taped over it. Is there a better way to do this for a better bottle? I'm afraid that the temps my get too cold for the ale yeast that I'm using and this is a chest freezer.