I would say you only need to do one or the other. Either use the egg tub with the lid covering it or use the water in the bottom of the incubator and no lid. I have never used a reptibator, but I personally use an egg tub w/ vermiculite & water as the medium and place a lid over that. This method seems to be pretty widely tested and accepted. Maybe someone else has used the reptibator and can be more helpful? Good luck!