I have an ehiem 150w heater in my sump set at 76 on the thermostat but the light is always on. I decided to play with it a little bit today and turned it down and the light/heat doesn't seem to kick off. The tank sits right around 80 all the time and the second heater in the sump doesn't ever seem to be on (set at 78). Im assuming that it needs to be replaced because the thermostat isn't working so i ordered a new one. Just wondering if this has every happened to anyone else?