C-Serpents mentions for their racks that there is a small gap at the top of the tub for airflow, so making holes isn’t necessary for some people. Is this how most company’s make their rack systems or is it usually a tight fit between the tub and ceiling of rack and holes would need to be made in the tub? Also, would that small gap encourage some snakes, like retics to try to push at that small open gap? Thanks for any help!