You want to run the heater from the pump circuit so the heat can't run if the pump is off.
I have a funny story about that... yeah, back when I was watercooling my computer and, in my infinite wisdom, decided to put the computer on UPS, but plug the coolant pump (120V fishtank pump) straight into the wall. Ever wonder what happens to an Athlon when it runs for 5 minutes without cooling?
