hey all, ive got a under-stair cupboard which is 3ft wide and 4-5ft deep, its 5.5ft at its max height and it decreases in height thereon as its under the stairs. I would like to grow 1-2 plants and am a little confused about the ventilation as there is no exists for a fan to go directly outside. The air will be confined to the cupboard. Do I need a carbon filter for 2 plants in such a small space? How tall will my plants actually grow?