I am not able to adjust the fermenter temperature by more than about 5 degrees F when I use the brewjacket temperature controller with the catalyst conical fermenter. I have two hypotheses: 1. the brewjacket tube being very close to the metal valve at the bottom of the fermenter is interferring with its functioning 2. Using more than 1 stopper to raise the tube to fit in the fermenter is reducing the amount of the tube that is inside the fermenter and thus in the beer. Has anyone had this problem and are there any ideas?