Reasons for using Zinc Anodes in chlorine-generated salt water pools or spas

Any time you have different metals (copper, stainless steel, etc.) in a salt water pool, you create a battery.  Some amount of current flows between the metals.  The electrons that make up the current are supplied by one of the metals, giving up bits of itself in the form of metal ions to the pool water.  This is called galvanic corrosion.  Galvanic corrosion causes plaster discoloration and metal erosion.  The best way to inhibit the effect of galvanic corrosion is to use a zinc anode. 

How it Works - Zinc is a metal that gives up its metal ions faster than other metals in the pool. In other words, the zinc anode will erode instead of other metals. This helps extend the life of salt cell and other metals within the pool (pool light, rails, heater, light niche, ladder, etc.). The zinc anode should be replaced after half of it has eroded.  Anode Zinc Balls can also sit in and weigh down the pool skimmer baskets.