Humid hides work super well just add one at the first shed sign and problem solved.


Hygrometers are odd beasts the analogue units from pet stores are not well constructed, the issue is the face card it is cardboard which when damp swells and distorts and often will jam the indicator needle impeding its movement. Digital probes work on the very tiny electrical changes of carbon when dry and wet. Electrical resistance. Anything that effects resistance will alter the probe dust dirt damaged cable poor connection on and on. They often have very poor accuracy to begin with and usually become worse as time passes. I use better made analogue ones they are resistant to debris and humidity and tend to take a lickin and keep on... you know. They only have one issue the magnet sucks and the steel disk falls off I usually replace (magnet) and glue better disks on.

http://www.amazon.ca/Brass-Analog-Hy...2986774&sr=8-8

This unit has a calibration screw to adjust the unit. A simple 'salt test' will check the accuracy to 1%RH although I have a number of these (14+) they all arrived less than 5%RH in error better than every digital unit I have ever checked.