I've been using my National Geographic 12 dollar temp and hygrometer from Walmart since I got my incubator in January. I've had hit or miss hatches and temps have been an issue in that, I believe. I recently bought a digital National Geographic temp/hygrometer and it is 3 degrees off from the regular one. The humidity is off also. (Not at home and can't remember by how much) I've been running it on the digital temperature reading of 100. The regular one shows 96 or 97. Which one should I trust??