Thanks for the reply. I went with the trial and error method for my first grow (CFLs in some stacked rubbermaid tubs). It worked out fine. When there wasn't enough airflow, i just cut more holes in the tub. The thing is, I am going to be building this cabinet as an eyepleasing piece of furniture. I'd rather not have yo make modifications after I build it initially. From looking around on here, I see others have cooled, ventilated and deodorized 400 watt cabinets with even just one 4" inline fan. I'll go for the 6" with nearly twice the cfm, just to be safe. A speed controller should help, too.