When you leave the fans running for too long after the lights, your plants will suffer the damages. Too much airflow reduces humidity, dries the leaves out, and can cause leaf tearing.    However, the amount of airflow shouldn’t be troublesome because you’ll need good airflow to inhibit the proliferation of mold spores. The longer the air stays stagnant in the grow tent, the higher the risk of mold infestation. So allow as much airflow in the tent without drying out the leaves.