Brian As you have a Jobo, you could try the Jobo thermometers which fit into either end of the Jobo water bath. I obtained two with my secondhand CPE 2 plus. Both agreed with each other and the Jobo temp dial which sets the element heater. I managed to break one so got another from Nova Darkroom but I am sure there are other stockists as well It was either £3 or £5- I cannot remember which. That one agreed exactly with the one remaining thermometer. That indicated enough consistency for me.