Of the 2 things that I wanted to toss out to the forum, these are both matters of my personal experience so please, no body interpret this as me telling anyone they are wrong...so disclaimer done My brewing goal this past year has been to do my best to be consistent in my brewing process so that I can monitor what the changes that I have purposely made have really done what I expected them to do and with the help of my own engineering experience has bought to this art, I wanted to back things up with measurable data and not hunches or taste or anything subjective. The inspiration for this has come from this forum and other forums along with a whole lot of commuter hours listening to the Brulosophy Podcast ( thank you Thunder Wagon for turning me on to that)! This last batch was to see for myself what the tempature on the outside of my glass Carboy and the temperature of the wort deep inside of the carboy as I had been reading that there could be enormous differences and that you really cannot expect to truly control your wort without knowing what your wort's tempature really is. A third variable was to see if those flexible stick on thermometers were usefully "close enough". My outcome was that there was never more then a 1 degree difference between the 2 and yes, the core temp was always the warmer of the 2. My methodology was to use my 2 Inkbirds that are always within point one ( 0.1) degree Fahrenheit of each other when measuring air temps. My "A" probe was stuck to the side of the 6 gallon carboy covered with some fiberglass insulation to isolate from the ambient air temp. Probe "B" was in a 12 " SST thermowell sharing space with my fermentation lock. I pitched my yeast last Sunday evening at about 75° then proceeded to further cool the batch down to the optimal range (59 to 71° F) for the Safale 05 dry yeast that I sprinkled directly onto the wort, no rehydration this time. As things cooled down to 67°F to following morning I could see we had some early signs of life with a burp or 2 every 70 seconds but no sign of krausen and .2° delta between the probes. With that, let the monitoring begin! 14 hours later we had a minor krausen going and had bumped up the wort temps by 1 degree and the yeast were doing their thing with off gassing happening every couple of seconds and some 11 hours later the next morning we were mid krausen, off gassing on the second and the probes both at 69.1°F. That night at full krausen the glass probe was at 69.6 and the thermowell was lower at 69.1°. At this point with the air temps in the basement climbing to the low 70's I reached for the swamp cooler method to keep things below 70° so the yeast would not peter out too fast creating the wrong esters in this batch of Red Trolley clone. I'm ending the week now at 68° and things starting to flocculate so no more swamp cooling. Now the plan is to give things another few to 4 days of rest before going to the bottles. With my temperature control methods a bit crude without a refrigeration chamber, I have been able to keep things within a five degree range overall which is fine with me but what I have proved to myself is that I do not have an enormous difference to concern myself with and that I am going to find a different use for that thermowell because my probe taped against the glass and the probe in the well and the cheapo tape on thermometer were all indeed close enough for what I am attempting to achieve; brew some decent beer at home for a decent price over and over!