vBulletin 4 has a lot of neat features (over all I really like it), but because of bugs, particularly when it was new, they should have called it vTrainwreck. I've heard a number of people criticize the editor they use in this version. So I suggest you go into your preferences and try changing the editor option.

If you use a false bottom (be it LECA/hydroton or some other false bottom) that allows excess water to drain from the substrate, you never have to worry about how wet the substrate is. Just mist on a regular basis and keep the ventilation to a minimum.