So I've been working with two pools in particular that I thought had Iron staining. Both pools responded well to Citric Acid treatments, and both pools suffered from some degree of recurrence of the staining. The staining was rusty brown-orange in both pools. I recently sent out water samples from both pools to be analyzed for Iron, and in both pools the samples showed no Iron was present. I spoke with one of the chemists at the lab, and they said the staining was probably organic, and they see at least a few cases every year where organic stains are mistaken for metals.
So I'm not convinced. I still think I'm dealing with iron. How can I test the stains to verify or rule out the various causes? I've been told a trichlor tablet should remove organic stains.
Vitamin C will remove metal stains, but will it also remove organics?
Is it possible for organic stains to return once they are removed? I always thought they formed when organic debris sat on the pool bottom for a long period of time (like over the winter in a closed pool).