there are a few things. you usually want more air coming in then going out. maybe a 4" exhaust with the 6" in. how tall do you want your plants to be? 60-16 for the bottom chamber makes 44 - 15 for the space you need between the lights and the tops that makes 29". minus the space for the growing medium and the actual dimensions of the light, you dont got much room. just make a separate cabinet for clones and veg.
Yea thats what I was thinking... or possibly just using a MH bulb or something... you think a 4" intake and 6" outtake would be suffecient?
i was saying you sound do it the other way around so more air is getting blown in than blown out. 6" in and 4" out would prob be fine for a cab like that. you will have plenty of air. itll save you some money too!