I was wondering if anybody else has had a problem with their heater for the TetraTec PF150 heater, model #HC100? I bought my filter and heater together about 2 years ago and about 6 months ago it started going crazy. It would never overheat my tank, but it would never heat it to the temperature I had selected. It would turn on and off at random times. Luckily I keep this tank in my office where I have 3 computers running 24/7, and the temperature is in the mid 70's at all time.