Cool Tube CFM ratings?

Does anyone know the formula for the amount of airflow required for 6" cool tube reflectors? I have heard everything from 80cfm per fixture all the way up to 180cfm per.. Im attempting to run a sealed room and I dont want so much suction that its creating negative pressure within the room.. but I also want the cooling effect to be as efficient as possible. Im guessing each size has a different recommended rating, and I would also assume that the amount of flow would increase as more fixtures are added due to bulb drag, length of system etc... Just wondering if anyone has found a chart with these formula's on them?

Cheers!