Passive intake or fan...Plz advise

I have a 2x4x7 tent with a 400 watt air-cooled light. What would be the best way to ventilate and reduce the heat? Since it's only 56 cubic feet, do I need a intake fan and just use a 6" exhaust? what are good quiet fans to use. Could someone please explain to me what is passive intake and is it ok for the plants. Thank you.

Passive intake basically means you don't use a fan to pull air into your tent, your exhaust fan "pulls" clean air into the tent while at the same time "pushing" warmer air out of the tent. There are other factors to consider, smell being the biggest. If smell is not a concern, then just hook up a 4" dryer duct to the light and then out the tent into a fan than can push at least 150CFM. You fan will pull air from the tent through the light, keeping you light cool and exchanging the air in your tent at the same time.

passive intakes only work for smaller plants and only in a sealed environment. you'll need a decent fan to be pulling the exhaust out of your area for this to work. i would recommend getting another fan for an intake unless you have an aircooled hood. in which case i would still use an intake but its not hugely needed as long as you have fresh air in the area and fans blowing at the top of the canopy. ive seen tents work well with passive intakes and some just have too many cracks that dont make it a vacuum.