1.How does the anode rod work? We all know that the iron tank will be eroded by oxygen and water or other corrosive elements. And the increase in temperature will accelerate this reaction. If your water heater has installed a anode rod, the rod instead of your tank will be corroded. The principle of this reaction is that aluminum/zinc is more active than iron. 2.Why should i replace the anode rod? Your water tank would be corroded faster when the anode rod has been consumed. The tank is in danger of leaking water and you are in danger of being shocked! 3.Aluminum zinc VS Magnesium Aluminum zinc alloy anode is the cheapest permanent fix for smelling water. Magnesium only solve smelling problem temporarily. If you dont waste your money and replace your anode again in half year later. We suggest that Aluminum zinc alloy anode is the best choice. The zinc is a key ingredient, since magnesium anodes will reek water to high heaven. 4.9.25inches Aluminum Zinc Anode Rod: *one size fits for a.o. smith Rheem, Reliance, Richmond, Kenmore, State, GE water heater *save your tank and save money *install in small spaces