Humidity is the hardest the GH parameters to control, and probably the least important.

This link I wrote for the FAQ might help.

My GH is often at the 90+% RH humidity level first thing in the morning, but often the humidity is much lower by the afternoon.

SB

Here is a link that might be useful: Humidity FAQ

I'm in zone 6 and my doors and vents are still open all night long. I leave one HAF fan running all night to prevent stagnant air pockets. Then at 9 AM the timers turn the other fans on. They go off at 6 PM when the sun goes behind the trees. My problem last winter was humidity that was on the low side. For this winter I bought several swamp-cooler type misters made for homes and apartments. I got them cheap at the Goodwill Store in town. :o) Only $12 for two of them. I also have an old water-breaker type I dug out of the storage building. This winter my plants will enjoy more humidity than last winter.