I have 4 different thermometers in a still air incubator. The digital reads 98. The one that came with the incubator reads 102. One, an aquarium thermometer reads 100. The other one, a regular thermometer reads 104. They are in 4 different areas of incubator. Which one do I go by? Last night, I did have 2 reading the same. I have not put eggs in yet, just trying to get temp right.