just fixed my yellow, Copper stairs....... I hate to say it but $40.00 at the pool store will remove the yellow overnight. Mine was to much metal in the water.. Copper stain's. The store sold me a bottle of this copper stain remover ( powder) I poored it on the steps and within a few minutes the stairs where white again. Actually, it was pretty amazing.. Make sure and tell them you want the powder that removes copper stains not copper in the water..... Should clear it up within 5 minutes.....