OK, I have 2 digital thermometer/hygrometers, one is pretty old and I used it a few years ago when I did a lot of hatching and I recently put a new battery in it. The second one is brand new I just bought a few days ago. I put them both in my empty incubator and noticed I was getting vastly different readings in temp and humidity so I thought I should calibrate. Since there's no way to adjust them I figured I could just make note of the +/- Differences. I did the whole thing with a little cup, 1/2 cup of salt and 1/4 cup of water, mixing it til the salt was slushy and had the consistency of sand, and put the cup of salt with the 2 thermometers in a gallon plastic freezer bag. 12 hours later 1 read 35% and the other 30% and I thought "No WAY they're off THAT much!" Come to find out my step mom had sabotaged it by opening the bag at some point about half way through to use one of the thermometers... So, I opened the bag, stirred the salt mix up again, very carefully set both thermometers back in the bag and sealed it and threatened everyone within an inch of their lives to NOT TOUCH IT!!! My step mom decided at some point it was in her way and moved it and knocked one of the thermometers off the stand so we had to fiddle with it while it was still in the bag to get it to stand back up again... IDK if this affected anything, but I'm pretty sure the humidity sensor was on the back so I HAD to stand it back up so it could read better... It's been nearly 12 hours since I sealed the bag a second time and one has been holding pretty steady at 50% and the other at 40% for the past few hours... Are they both really off THAT bad or am I doing something wrong? It's supposed to be at 75% isn't it? Should I start all over with new salt and new water and put each one in a separate bag? I even made sure to use purified water and not tap water. Any insight or ideas would be very helpful since I have eggs sitting, waiting to set in the next couple of days!