I am using the one from secret jardin, the dark room 120, and its a lil over 6.5' tall. I dont veg mine long, so heighth isnt really an issue for me. I never open the bottom vents either. Im too lazy to go open and close them at lights on and off, and I dont want light leaking in from there. I just use a little inline fan at the bottom to bring in some fresh air, and i have some ducting hooked up to it as well, to make sure light isnt getting in from there. Its completely dark in the room at lights off, as I have went in the tent and closed it off to see how much light was getting in, and I couldnt even see my hand 2 inches in front of my face. The only time I really have to do anything is at watering time. Other than that, its set it and forget it.