this grow is in an attic I do not have a fan in the window would a window fan or air conditioner be the best for this instance. I have a osscilating fan inside the grow tent but as for the air that is inside the room the air is really not being circulated that great. But as for the yellowing is that a nutrient or air problem I cannot tell as this is my first grow? Also if a fan or ac is needed please tell me I will go out now to get one.