Flexwatt and a Herpstat. You can run it along the back area equal lengths on all tubs. Make sure to get the grounded version since that rack is metal. I would also use black contact paper on the outside 3 walls of the tubs that you aren't looking at so the snakes feel secure. I use put black contact paper on the outside of my tubs for that very reason. That's a mighty big tub unless you're throwing in adult females.

Regards,

B