installed a gfi plug

[TheReefGeek]

In addition to GFI outlets and powerbars NOT on the floor, you should use a grounding probe for safety. For example, if your lighting unit falls into the tank while you have your hands in it, the GFI wont trip, but a grounding probe may save your life.

I would also test your aquarium pretty regularly for stray current as well, to make sure any of your devices are not failing/faulty.