The Herpstat will control one of the heat sources... not both... The Herpstat II will support two heat sources... But you don't need the top heat source if the room is warm enough. If the room temps are in the low to mid 70's, then the flexwatt will handle the floor temps, and the ambients should be okay... if not, you can just put a CHE, or red incandecent at the proper wattage to adjust those ambients. (50-75 or 100 watts)

You might also consider going with a plastic tub setup... (Sterilite, Rubbermaid, Isis, etc..) ...much easier to control temps/humidity.