Over power it!!!!!put a 6"just on just the light.then add what ever fits ya vents on intake and exhaust.then add 2 cheap fans on inside to blow air around the garden.im currently running 1 6"inline on a 600whps cool tube.3 small computer fans I pulled from my cheap broke ass led light.2 small car audio amp fans for exhaust,and 2 el cheapo fans directly under the light to blow around more air.this is a 24x36 setup.set in a room that has no ac,on a hot day it will b 96f in room,but box doesn't get over 78.as far as carbon filters,I don't need them,never used one.to my knowledge they r no good for high humid areas such as mine.and i love to smell dank!!!!a friend of mine use's ona.works real well,but gets expensive,buying ona every week.