The greatest obstacle of a hot water tank is to overcome the destructive forces of the hot water and the impurities in it. One solution to this problem is to place a sacrificial rod made of manganese in the center of the tank. This rod attracts the impurities in the water and is attacked by them. The idea is to protect the enameled steel tank and sacrifice the rod in the center. The disadvantage of this approach is the smell that can sometimes result when the water attacks the rod. The smell is like sulfur or rotten eggs and it not pleasant. A lot of homeowner remove this rod by unscrewing the bolt that it is attached to. Removing the rod usually works but it also shortens the life of the tank. I recommend consulting a plumber for more information about this procedure.