I am having a heck of a time calibrating my thermometer and hygrometer for my incubator. I've done the crushed ice method for the "out" reading on my probe thermometer, and I swear it gives me a different reading every time! The last time I added more ice and think I've finally got it figured out as 1.4 degrees too high. Same thing with the wet salt method for calibrating the hygrometer. I've got three digital Walmart combo units in the bag with the cup of wet salt, and one is definitely broken because it always reads 20% no matter what, but the other two are both reading the same - 61%. It should be 75% right? I'm having a hard time trusting these things, even "calibrated." Would I be better off with the little round analog reptile ones?