Ventilation question. +REP

If my grow room is sealed well enough with strong enough exhaust will I need to have an inline fan sucking air in. I am going to grow in my bathroom with the exhaust going out the ceiling into the outdoors. I would rather not remove my door in replace of an in take fan. Would it having the door closed cause a vacuum effect and draw enough air from the crack underneath the door.

no you do not have to have an intake if the exhaust is sufficient just need an opening for it to come in

If you do Increase The air flow high enough you will have to open up alittle. I good rule of thumb is "do you hear nails creaking?"

And no fan needed..

Here is a good rule of thumb:
1 square foot of intake for every 500 CFM of exhaust.