I've been keeping my fermenting bucket in a bath of water with a fish tank heater to keep the fermenting temps up through the winter months in CT. I'm not convinced that the bath temp is reflective of the brew temp. I did some testing with just water and observed that the temp in the middle of my fermenting bucket was 5-6 degrees higher than the bath water, and if you add the heat of fermentation it could be another couple of degrees (I'm guessing). My theory is that because the bath water is exposed to the cool air, it doesn't loses more heat to the surrounding air than the covered and sealed fermenting bucket.
Has anyone ever put a small hole (maybe with a grommet) in the top of their fermenting bucket for a 12" thermometer to be able to monitor the temps as fermentation is taking place without opening the lid? Is there a better way? I've tried the stick on temp strip, but I'm not convinced it was too accurate.
I'm trying to make the most of my basic equipment to really nail my temperatures, especially for a saison I'm planning on brewing.