I have just completed an orchid growing case 18w x 42H x 35W. It has a humidity tray on the bottom and a 24" 4 tube t5 fixture on top ( 8000 lumens) the back wall and right hand side wall are solid plastic board painted off white while the front and left end are 1/4 plexi, The front panels are on sliding tracks for access,. ventilation is provided by 6 - 6"x1/2" ports just above the hum. tray and 4 small doors in the top that can be adjusted. The combination of bottom ports and top vents give a chimney effect and provide a constant and adjustable updraft. All good so far but I am having trouble achieving the humidity levels I want:60-80%. I have considered a small muffin fan mounted just above the Hum. tray to speed evaporation but can't find anyone who knows how to hook one up to a 120v. AC outlet. Also this may not be enough. Perhaps there is a better option but I would prefer to avoid a humidifier. I note that some Orchidariums use an aquarium bubbler and air pump. Interestingly my first case is identical in design but only 15" x 15" x 22" and maintains 70% most of the time. Can some one please solve this mystery for me?