What is more accurate? A Fermometer or a Johnson Controller, with the sensor taped to a glass carboy.
I ask because I'm getting two different readings on my carboy. My Johnson Controller is reading 73 degrees and the Fermometer is reading 78 degrees.
I should note that I have a piece of foam insulation covering the sensor as to not allow the air in my fridge to interfere with the reading. I also have a fermwrap taped to the carboy. It is on the opposite side of the Fermometer. I guess the glass could be absorbing the heat and throwing off the Fermometer. But why not the Johnson Controller?