For the thermeter accuracy, first calibrate them. Then use several to check the temperature and then average the readings.
Or buy a Brinsea Spot check.
A very accurate, easily read incubator thermometer specifically designed for incubation with a range of 32° - 40°C (90º to 104ºF).
Ten times more accurate than most digital thermometers, it reads to 0.1ºF with an accuracy of ± 0.2ºF. Switchable between ºF and ºC.
The remote probe on an 18" cord fits through ventilation holes of the incubator or brooder so that the thermometer can be left outside the unit for easy reading.
Battery life is about 6 weeks in continuous use, but very much longer if switched on just as required.
I got a.thermometer at Wal-Mart but I'm thinking I need a reptile one. or something. the one i got is calibrated and so far.its about 5 degrees below the digital reading on the display. I looked at the spot check but I want to get one that I won't have to wait for shipping. any suggestions on a thermometer i can get from Wal-Mart or a pet store?