Newbie here with a newbie question: Does anyone use 2 fans on the same duct run to cool sun tubes or any air cooled reflector? One on the intake blowing air into the ducting and one on the exhaust sucking air through as well. Seems like most people have high CFM fan sucking air through. I have two 6" sun tubes and I'm planning on getting two 600w ballasts and bulbs. They are going to be run in series (on the same line of ducting). Also, what CFM would you recommend if it is just one fan? Thanks in advance for any info!

The two fans will increase air flow on long runs. As long as your inlet to the grow room is passive you should be fine.

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Any advice I may give or things I may say are of a hypothetical nature and should in no way be taken seriously or followed by anyone.

Thank you f1tzg3r4ald. I should clarify that I am planning on a sealed room with CO2. I am bringing cool air in from the subfloor and venting it out into the attic. My room is 270x270x100cm (9'x9'x8'). I'm keeping my duct runs as short as possible with as few bends as possible. I live in NorCal and it can get hot here so I'm trying to keep the lights as cool as possible so the A/C doesn't run as much (and so I can place my lights as close to the canopy as possible as well).