Crush up some vitamin C tabs and sprinkle the powder on a spot. If the yellow clears right away, it’s probably iron. If the test verifies that it’s iron, you can get bulk for a whole treatment.
You can use a product like this:
Stainfree Extra Strength | Backyard Water Care | Natural Chemistry
Make sure to get the "Extra Strength" product and not the regular product. The regular product is not ascorbic acid. The regular Stain Free is citric acid.
Or, just Google for bulk ascorbic acid. Example:
Ascorbic Acid (vitamin C) | Bulk Apothecary
You can use a product like this:
Stainfree Extra Strength | Backyard Water Care | Natural Chemistry
Make sure to get the "Extra Strength" product and not the regular product. The regular product is not ascorbic acid. The regular Stain Free is citric acid.
Or, just Google for bulk ascorbic acid. Example:
Ascorbic Acid (vitamin C) | Bulk Apothecary