A cathodic protection system for a tank has an anode which comprises a long extendible coil of wire of a valve metal coated with a suitable electrically conductive ceramic material. The coil provides reduced electrolyte resistance and power consumption. At installation the coil is extended to provide the anode length desired for the particular tank. Each end of the anode can have insulation to provide the desired dielectric standoff. The insulation of the lower end can be in the form of a the weighted element to stabilize the position of the anode.