The current efficiency of magnesium anodes is about 50%, and may be lower due to environmental effects. When the salt content of soil or water is low, the current output is small, and therefore, its own corrosion is relatively large. When the soil resistivity is high, the anode output current is small, and the anode surface is prone to passivation, which further increases the grounding resistance and further reduces the anode output current. At this time, there may be no significant change in the open circuit potential of the anode or in the pipeline potential measured at the energized point. When the temperature rises, its own corrosion is intensified, and the efficiency is reduced, so the use temperature should not exceed 32 ° C in salt water or salt water; In fresh water, it should not exceed 45 ° C, and in seawater, its life is very short and should not be used