Should be more than enough. I'd run at 75% speed though. I've been battling the carbon filter thing forever. Finally got a 8x24 phresh hooked up to a 440 6" (w/ reducer) because when I was running the 440cfm on my 6x24, it was not enough. I think it's a good idea to get an oversized filter for your fan, or get an oversized filter/fan for your space and run at reduced speed. 8x24 should be great for a 4x8 tent (what I use) even with some dank weed. My 440 cools my 2 600's no problem.