That is why it is so odd. I've changed nothing but put the thermometers inside the box and I took a chance once and opened the lid quick to move the gage out of the corner and put the outside probe close to the main controller and it still reads different. The other incubator reads a difference of 1 degree from inside and outside temp. They are the same thermometer. There is water in the bottom of the foam incubators and 1 sponge in each one. I news to get the humidity up more, but am not entirely sure what else to do. I may have to as another sponge, it says it is 53%