My "new" little indoor greenhouse has 6 biax 40 watt bulbs (18900 lumen output). Should I be concerned/careful about moving plants from the east windowsill to this new light? Any thoughts on how long the lights should stay on? Should I start with a shorter time (say 8 hours) and gradually build up (to say, 12 hours)? (I'm completely new to growing under lights!) Thanks!