Use two separate outlets on the energy bar. You can change the outlet types in Fusion. Change the control type (seen in the picture) on one of the outlets you are not using to a heater outlet. (This prevents a failure if one outlet goes bad.) You can then set each outlet individually. I run three heaters in my system. The system uses two on a regular basis, but the third will come on, at about .3 degrees below the others, if one of the others fail or the temperature starts to fall because the house is suddenly very cold. Any two of the heaters are sufficient to heat the aquarium, but no one heater is capable of heating the aquarium to the point of killing everything by itself. This guards against a heater sticking on, which should be impossible with the Apex monitoring temperature. Hope this helps.