I have recently made a 4'L x 2'D x 3'H chamber out of lumber. I then covered it with clear painters canvas to keep heat and humidity inside. I put 2 4' t-12's and they keep the chamber at a constant 80 when on. I have recently been researching and have found Holmes products to be enough to keep a small greenhouse like mine sustainable for weeks on end. I have decided to buy the thermostat regulated twin window fan for exhaust that is 49.99 to keep cool air coming in from outside and for overall air flow. I want the cool air humidifier that has a humidistat for 49.99 also. This takes care of light, humidity and air flow inside. I think that having vents near the top with the possibility to vent air out with a small fan will take care of air flow. The humidifier will keep the humidity up reliably well above 70 percent for a period of days which is not bad for a 50.00 product. The humidistat and thermostat on the fan will help a lot. I keep my HL neps in orchid pots in trays and water every time it dries up and I notice the sphagnum on top drying up. With the humidity its not usually a problem. I plan on probably getting rubbermaid tubs in place of the trays as they do break down fairly fast when moved. Also the tubs will give me better depth to keep water underneath the plants while not sitting in it. The whole thing will cost me 20 dollars in lumber. 5 dollars in clear plastic tarp. 50 for thermostat fan and 50 dollars for cold air humidistat controled humidifier. and 20 dollars for the two lights and bulbs. very cheap and once set up will be reliable. I have tested this out with sucess and this is the finished product. Once its finished I will post tons of photos.