* *An ultrasonic humidifier works by the same principle as a fogger. *Both have metal discs that break water into a very fine mist. *Ultrasonic humidifiers just have a fan built in to force the mist into the air. *The foggers will work for a small terrarium, but they are not as effective in a larger area. *Because the foggers have to work longer in order to bring the humidity up, the metal discs wear out and have to be replaced. As I mentioned previously,I've had my ultrasonic humidifier for 10 years and haven't had to replace anything. Ultrasonic humidifiers can be found at drug stores, hardware stores, etc. *I see that Amazon.com also has honeywell "visible mist" ultrasonic humidifiers for a good price(note "cool mist" is not the same type of humdifer, they depend an evaporation wick).
For a 60 gallon terrarium I've used a humidifer/humidistat combo and it works good. *If the terrarium has good ventilation, the stagnant air is flushed out on a regular basis. *The large chamber I'm building now uses a 4" CPU fan hooked up to aluminum dryer vent hose. *The fan is positioned outside the chamber, pulling in fresh air, and the vent hose is directed inside the chamber. *The output of the humidifier is directed into the vent house to insure that the air is humidified. *This creates great air flow, and also allows the humidifier to work more effectively. *I had the system set up with just the humidifer and it took about 10 minutes for the humidity to raise up to 80%. *With the 4" fan it only took 2 minutes. *I've found that it even though the humidity is high, no condensation forms on any surface (sides, bottom, leaves, etc). In hydroponic circles this is referred to as "dry humidity". When the humidstat is on, I can literally dial in whatever humidity level I desire. I'm hoping it will create an environment suitable for highland neps....we'll see.
Some excellent info can be found at Josh's site (he gave me advice for the ventilation system):
check out the highland cultivation section. *It's not quite complete, but Josh is happy to answer email questions.