Originally Posted by TLTGF
That's a grounding strap for your tank. You place the metal rod in the tank or sump and plug it into the wall. Theoretically, if your heater, PH's, or pump somehow find a ground in the tank the fish don't get zapped, the free electricity will find this ground and go out of the tank. Stray electricity and water = not fun.
Thank you. It was my last puzzle piece.