I am not going to debate racks versus tanks vs pvc cages but generally people with tanks use CHE's or light bulbs because tanks don't hold heat well. A tank is not an ideal enclosure for ball's. To make a tank more efficient you can cover the screen top with aluminum tape, insulate the sides and back with foam insulation etc. etc. there is a good sticky I think that helps people with tanks make them work.. I am keeping 30 snakes warm with under 300watts. and that 300watts is only running at 10-20% according to my thermostat so really its only drawing 60 watts.