What
@Tejashidrow said, get a lock on the door if you can (the Grow room). Keep the old knob and put it back when you move out. Hell, change all the damn locks. Most leases will prohibit it, or stipulate that you must notify the landlord and/or leave the lock when you go. But fuck that, do it anyway, they aren't checking out your deadbolts for tampering and if it somehow happens that they find out, the worst is usually that you are out the cost of the lock. Me personally, if it was a choice between having a story ready to explain a new lock and possibly having to leave it or pay a fee for breaking a rule, vs. having a maintenance man or employee walk in on my grow, I know which one I'm going with. That said, heed the wise advice of others here when they say to keep it to scale. A room has a 15 Amp breaker. Don't fuck around with putting in a new one, work with what you have.
Carbon air filtration is an absolute must; I've seen someone here mention oversize filters eg 6 inch filter to 4 inch fan. I think that's an awesome idea.
Be nice to your neighbors and don't stick out.
Edit: forgot to add that if they find out you switched your locks, you can lay into them about not giving advance notice of entry (if that's what happened), which is the law where I am. Last time someone needed into my place I knew six days ahead of time.