There are lots electricity conductors. As an example, metal is a great conductor of electricity. Another strong conducting element is seawater. Seawater is ... read more a good conductor of electricity and freshwater is a bad one. So you see more corrosion in seawater rather than freshwater. Other factors include how much oxygen is present in the water. The more oxygen there is, the better the chance of corrosion. Areas that seek out oxygen can become anodic and corrode. Another place that increases corrosion is when pollutants are around. Flow rate can play a part as well. What's also interesting to note is the temperature can increase corrosion rates. Rule of thumb is for every 18 degrees Fahrenheit the rate of corrosion doubles. Last thing that we will mention that affects corrosion is bio-organisms. They remove the protection you apply onto your boat or change your environment into a corrosion-filled one. If you have any questions regarding Mercury outboards and anodes, please call 1-800-743-1123 to have all our questions answered.