Help with airflow. I've got an extractor and 3 circulating fans. Would a powerful inline fan be better than the 3 circulating fans

passive intake should be 2-3x larger than the exhaust port... i've read that somewhere.. there's a rough guideline for sizing it. it looks like your air exchange is fine. your duct used and drag from the passive intake ports will reduce CFM of exhaust, but you have plenty. Always good to have more than necesssary and run the intake/exhaust fans at 50% to reduce noise and increaase longevity. it's probably possible to kill 2 birds with one stone with a well-positioned intake fan, but the circulating fans you have a slightly different function. since you already have 3 circulating fans and a powerful enough exhaust, you should be fine.