It's me again....with a stupid question. If it's not one thing, it's another!

Foster is in a shed phase right now and for the life of me, I can't keep the humidity up unless I spray every hour, on the hour and sometimes in between.

When I got this bag of substrate (exo-terra bark) it was so damp that the humidity was through the roof (90% range). But, now that it has had some time to dry out (even what is left in the bag) I can't seem to get the humidity high enough unless I spritz constantly.

My question is this....how much spritzing is too much? The bark isn't wet but with spraying as often as I am, should I be concerned about mold, bacteria, scale rot or anything else? She has not come out of her hide that I know of the past few days and I know of and I'm sure the bark in/under her hide is dry but I am just getting worried that constantly spraying might be causing more problems.

If I don't stay on top of the spritzing, the humidity will get down to the 40% range. After I spray, I can get it up to 75% but it won't stay there long. I've got an UTH on the warm side and a black light on the cool side to keep the gradient up and unfortunately there is not much I can do about that. I have most of the screen covered with plastic and when I do spray, I spray mostly glass but if I want to get to the target humidity, I have to spray the substrate also. She also has a good size water dish in her 20L tank.

This is the worst humidity problem I've had since owning her! I am really hating this exo-terra bark!

(in person I don't talk much but I guess I more than make up for it in my posts....sorry for the overkill)

Thanks!