The only way to eliminate these stain-causing metals:
From pool and spa water
Watch this video to see how CuLator Metal Eliminator and Stain Preventer works to remove and eliminate metals from pool and spa water which prevents pool stains on the surfaces of your swimming pool. CuLator helps prevent copper stains, iron stains, manganese stains on gunite, fiberglass, and vinyl pool surfaces. To prevent stains, metals must be below .3 ppm (parts per million). CuLator can reduce metals to 0.0 ppm.