What do I use to control humidity in a fruiting room?

For a small setup, a spray bottle and a humidity tent or shotgun chamber over damp perlite are enough. For a room, an ultrasonic humidifier on a humidistat holds humidity at 85 to 95% without constant misting. Pair any humidifier with fresh air so you get damp surfaces, not standing water. A simple hygrometer lets you see what is actually happening.