I have a 150w Aqueon submersible heater in one of my tanks that I got from PetCo. I have noticed over the last few days that it makes a loud, intermittent clicking noise every once awhile. The noise appears unconnected to the heater turning on/off. It is holding temperature, but the noise is very noticeable, and can be easily felt as movement if holding the top of the heater when it occurs.
Should I be concerned with the safety of this item? Should I be getting a new heater for the tank?