Just upgraded Wraith to a 25-watt Hydor Theo submersible heater, from one of those flat plastic credit card-sized doohickeys. He's in a filtered 3-gallon glass tank with a lid.
His tank started at 74 degrees this morning (which is why I upgraded heaters... too cold, I know). I set the control at 81, but in the last 6 hours his water temperature has only risen to 76. I'm worried that if I set it higher, I might inadvertently cook the guy... But five degrees between setting and actual seems like a big discrepancy. The thermometer is a glass one hanging in the opposite corner of the tank.
Any experience with this?