you need more airflow than what a 300cfm can handle ... my 250cfm duct fan (vented outside) doesn't even handle my little 400HPS ... seems like you can never have enough ventilation ... and, you are way off on your plant count ... with a good hydro grow, you can fill your cabinet with one plant ... my 2x4x8 has 2 hydrofarms, and that's too much plant, really ... :smokin: