great post szampino It is excellent advice essikr. It is more important to make sure the pool is sanitized. Then you can deal with the stains, this way you won't have to shock right after the ascorbic acid treatment, so that the sequestering agent has time to sequester all of the metal that has been brought to solution by the ascorbic acid. I know it is frustrating, but once you get the idea you will be able to know your won pool, and how it reacts to chemicals you add.