What is PASSIVE intake????

Hello all, I just finished setting up my grow "tent" in my closet and I need some help with ventilation! I will be growing 3 plants and using several CFL lights so heat wont be a serious problem since I am using CFLS. I am planning on using a carbon filter at the top of my "tent" hooked to a fan for the exhaust. My question is WHAT do I do for airflow into the "tent"? I have read that cutting a hole in the bottom of the tent will work, but I don't know if that would be sufficient. My "tent" is 4x6x2 so its not big, but not small either. Any advice is appreciated!:smokin:

That sounds good. If the intake temperature is low enough to keep the plants happy (75º or so). Otherwise an intake may be ducted from outdoors to the tent.