Voltage can enter our aquariums by several means, one of the most common is induction. Induction is the process by which an electric current, an electric charge, or a magnetism is produced by the proximity of an electric or magnetic field. Let’s see; do we use any magnetic fields or electric charges in the proximity of our aquariums? You bet we do. Power heads and large water pumps have both. Fluorescent lights have a strong electric charge in that tube. As air bubbles burst at the surface of the water they spray salt several inches. Salt creep or salt spray can form and give electricity a path from lighting, heaters and powerfilters to find the aquarium water. Because of the conductive properties of salt water all equipment (heaters, lights, powerfilters etc.) should be kept clean of salt spray and salt creep. Non submersible heaters should never be used on a marine aquarium. Not only because of the potential of stray voltage in the aquarium but they will eventually stick in the on position.