Good job getting the temps down. Razor's right, you do need a bigger fan/ blower. Better to have one that will move more air than required. I have my garden in a 122 csqft tent with one 600w and a 465cfm blower pulling hot air out 24/7. No air cooled hood or anything, just the cool negative air pressure coming in. Over the summer temps rose and at one point the temp in the room where I keep my tent was 85 but the air inside the tent was sitting right at 79. Trick is to have a BIG fan and a somewhat sealed tent to help create the negative air pressure to help keep temps cool. You know you have good negative air pressure when the tent walls get sucked in. I've tried leaving the tent open before and it actually ran hotter than when closed up due to the loss of negative air pressure.
Try to get a bigger fan or add another to the one you already have. Not sure what kind of tent you have but I know alot of them you can fit two fans in them.