Most importantly, don't use the top for storing extra tubs, etc. The weight makes the tubs very difficult to slide out and if one of your babies is near the top it will get crushed when you're pulling the tub outside. I found out the hard way last year and lesson learned. I also loosened the tightening nuts on top so tubs slide out faster. I keep baby mtn. kings (knobs) in separate tubs, with bottom heat, sitting on shelves using containers with snap on lids. They are very tiny as hatchlings and growth rate is slow.