I have bought a gazillion thermometers and hygrometers for hatching and finally decided that the simplest is the best. No matter what type of thermometer or hygrometer you use ALWAYS calibrate them before each hatch. I originally bought the one at walmart ($9) that has both the temp and humidity and thought it would be great to use. After having 2 terrible hatches when I finally calibrated it I found the temp to be off by 4 degrees and the humidity was reading 12% lower than it actually was inside the bator.Yes the digitals are easy to read but they are very difficult to calibrate. I ended up going on ebay and buying these: scientific thermometers
They cost $20 but you get 10 of them. $2/each which is pretty cheap. The only drawback is they are in Celsius but after using them for so long I find them easier to read than F. 37.5 C =99.5F
These are very easy to calibrate too. Just fill a glass with crushed ice and water to the top and let it sit for a few minutes. Stir it up a little and then place the thermometer in the water making sure it does not touch the sides or bottom of the glass. Your thermometer should read 0 Celsius. If it is off you just need to add or subtract and you know what the correct temp is. I like these because you have extras in case one breaks. You will never need another thermometer besides these.
Next is the hygrometer I use. I found these on ebay also and they work wonderfully. They are easy to calibrate and have not failed me so far. I have 2 in my cabinet incubator and 1 each in my hatchers. HYGROMETER
I also bought one of these to calibrate my hygrometers but you can simply use Salt/water/ziploc bag to do the test also. Look on Youtube for a few videos on how to do it. These little bags work great and are reusable. I figured for $4 I didn't have to be messing with salt and making a mess every week. Just pop the hygrometer in and let it sit overnight. Calibration Kit
So for a total of $31 I will never have to buy another thermometer or hygrometer again. I will never have to worry if my thermometer or hygrometer are working correctly because they are always showing the correct readings.
They cost $20 but you get 10 of them. $2/each which is pretty cheap. The only drawback is they are in Celsius but after using them for so long I find them easier to read than F. 37.5 C =99.5F
These are very easy to calibrate too. Just fill a glass with crushed ice and water to the top and let it sit for a few minutes. Stir it up a little and then place the thermometer in the water making sure it does not touch the sides or bottom of the glass. Your thermometer should read 0 Celsius. If it is off you just need to add or subtract and you know what the correct temp is. I like these because you have extras in case one breaks. You will never need another thermometer besides these.
Next is the hygrometer I use. I found these on ebay also and they work wonderfully. They are easy to calibrate and have not failed me so far. I have 2 in my cabinet incubator and 1 each in my hatchers. HYGROMETER
I also bought one of these to calibrate my hygrometers but you can simply use Salt/water/ziploc bag to do the test also. Look on Youtube for a few videos on how to do it. These little bags work great and are reusable. I figured for $4 I didn't have to be messing with salt and making a mess every week. Just pop the hygrometer in and let it sit overnight. Calibration Kit
So for a total of $31 I will never have to buy another thermometer or hygrometer again. I will never have to worry if my thermometer or hygrometer are working correctly because they are always showing the correct readings.