My dehumidifier reads 60%RH but my thermostat with the wire hanging right over the top of the canopy reads 30%RH. The dehumidifier is set up about 5ft from the thermostat. Which reading should I go by?
Geez, huh? I guess I wouldn't know which to trust either... A very accurate hygrometer shouldn't cost much. I have a pal who's really into his Cuban cigars and he gave me a very good portable digital hygro called a Western Calibur III when he had an over the top humidor built into his home.
heat from lites will dehumidify the air near the bulbs more that what the actual room humidity is. I'd rely more on what the dehumidifier says because its likely a more accurate reading for the room rather than the place below the lites.
Carefull you dont dry the leaves TOO much. If the leaf blades begin to roll/curl upward. they are too hot, or dry. Overheated leaves might also begin to turn whitish.
I've had the same "problem" with my stand alone hygro's reading differently than my dehumidifier. I just use more than one hygro, and sort of get an average. Use your hygro's as a baseline, as every environment will have different characteristics.