You can set the fan up like this - scrubber - fan (sucking through scrubber) blowing through cooltube, and you cant see the exit to the right, up and out. This keeps the light cool and takes care of smell with one fan. The intake is on the far right, so it pulls air through the whole room, promoting airflow. Theres also another fan circulating air in there.

Your 449 should be adequate. The intake should be 1.5- 2x the size of the exhaust IMHO, you don't want to restrict the ability of the fan to pull cool air in