I can see your problem already. You've got the 8" sucking air from inside, through the scrubber, and pushing it through 4 hoods. You should be pulling micro-filtered air from outside, in through your hoods, pushed outside to a carbon filter. Even with 4 hoods on 1 8" fan, you shouldn't be where you're at temp wise. I've never liked the conventional "scrubber" with it being in the tent. It forces you to push the air though the hoods rather than pull it. It never has made sense, considering most people aren't using cool tubes or pressure sealed hoods.... Besides, temps drop when you introduce fresh cool air, utilize it, then exhaust it, not just use exhaust all the hot air in the tent. Gimme a bit to MSpaint up a diagram of my venting.