I don't use a hygrometer in any of my tanks... I'm not too anal about humidity and my frogs don't seem to be either. If there is condensation on the glass humidity is nice and high, but if there's not I'll give a light misting. That's just how I've been doing it all along, and everything is going great. Also most frogs don't prefer to be literally wet, so don't mist so much that the soil gets water logged and such.
Yep, i don't use one either. In the beginning before the frogs went in I had a cheap walmart hygrometer that I used to double check humidity and make sure it was good. Now I know it's a whole lot easier to look for fog on the glass though...
I have three different meters in my one tank. they all read a different humidity. One seems to be stuck on 80, one seems to be stuck on 90 and the third one moves from 83 to 99. So I am not sure which one is right or if they are all wrong. So like the others on this board I think the moisture on the glass is the most reliable.
I agree with those that posted above. I have a meter in one of my tanks and I use it as a guage for all the rest of my tanks as they are all similarly set up. I've double checked by moving the meter from tank to tank just to be sure though. Hope this helps.