Safe. Powerful. Amazingly Effective. Iron stains appear as a brown or rust discoloration. Copper stains look like blue, grey or black spots. Black spots can also be stains from manganese. Organic stains, commonly from leaves or tree fruit, often retain the color and shape of the object. If a stain is not caused by algae, chances are it is a metal stain. Use Lo-Chlor Multi-Stain Remover as an over-all treatment or as a spot treatment to remove stains and treat with Metal Gone to prevent further staining.