I have one ten inch cann fan cooling them all. It was doing a great job before I extended it to curve down outside. Too much light was leaking in so I had o do that along with spray paint the inside of the ducting black try to reduce as much light coming in as possible. It still definitely does the job, but noticeably less airflow. So the top left is connected to two hps then there's the fan thats in between veg and flower then 600 watt mh, followed by 1000 watt my, followed by another 600. Iol it's pretty warm I wouldn't say hot though.
All the lights are in 8" cool tubes, all one straight line