Cobble™ Oxhide - Concentrated Sprinkler Rust Remover

For a ready mix it works well way too expensive for what it is, buying oxalic acid and mixing yourself might cost time but the savings are unmatched

Used this to remove iron stains from fertilizer left on travertine patio and can’t believe how good it worked. Great product

did not remove rust stains on white travertine from fertilizer beads even at 3 to 1 ratio and scrub brush as directed in instructions