intake at the bottom of the container exhaust at the top and make sure there not directly across from each other you want turbulence in there so that the air mixes and all the heat is taken out not just the heat in between the space where your fans are which is what happens when there directly across, so if i re did mine the intake would be in the bottom corner and the exhaust would be on top in the opposite corner diagonally. what are you going to use for fans? if you end up going with CFLs and want to grow 3 AF'S 4 26w 6500k bulbs and 4 26w 2700k bulbs would do fine for the whole time all you would need would be 2 light sockets and 6 Y split sockets to run the 8 bulbs