Since i have such a small space to grow in, i have...

Personally I think one blowing above the canopy blowing the heat away from your flowers and one below giving aircirculation would be the best options. But if Ik had to choose I'd go with above the canopy first. But I use a HID and it's giving off a lot of heat. I really don't think there's one good answer. As long as all the air in your growroom moves around I think you have the desired effect. If you're in doubt, Maybe try out different possitions and use some insence or smoke to see how your air moves around and if there are deadspots in the room. You don't want the fan to counter the airflow the airpump is creating. Airflows have many parameters that influence them like heat differences, pressure differences, venturi effects, possitions of intake and outlets,... Kinda hard to just say this will work better all of the time.