Who Gives A Fish Forums

If you're using a power strip, try plugging the heater directly into the wall. I've seen cases where cheap strips introduce noise. Also, check your GFCI outlets—they can trip if there's a ground fault, but sometimes they don't catch small leaks.

Stray voltage can definitely mess with your fish. I use a multimeter to check for it. Just set it to AC voltage, stick one probe in the water, and ground the other. If you get a reading above 0.5V, it's worth investigating. Also, check your heater and pump for leaks. Had a similar issue last year ...