I actually just picked one up a couple days ago due to a little scare I had. believe it or not, I reached into the tank and I felt a shock in my finger. I was thinking to myself what the hell was that? It wasn't a really painful shock more like a shock you would get from an electric prank pen. I unhooked all of my stuff one by one testing the water with a multimeter and as it turns out my extension cord had gotten chewed on by my pup and salt creep had managed to find the chew marks. So I bought the GFCI outlet and now everything that runs to the inside of the tank or around sump area is plugged into it!