humidity is a funny thing to work with... I have found that a big bowl of ice with a sponge on top is perfect for the slow addition of humidity, and an A/C or extra circular fan (or combination of both) is good for reducing it. Combining both methods (both increasing and decreasing at the same time) usually produces a controlling effect, so you can tinker with it and find the right settings for yourself (I.E. the bowl with ice cubes sits next to a circulation fan, and the A/C runs for 15 minutes out of the hour in my room maintaining the desired humidity).