Concrete Rust Stain
A home remedy for concrete rust stain is lemon juice. Squeeze a lemon on the stained area or spray lemon juice on the stained area. Let the lemon juice remain on the concrete for at least 5 minutes, then rinse with water. If this method does not remove the rust stain, use vinegar or orange oil and follow the same procedure as with lemon juice. If these do not remove the concrete stain then use commercial products that contain oxalic acid. Take proper safety measures (eye and hand protection) and read the instructions on the label before using. Oh and next time don't use that product. Greensand is a much better iron source product, is organic and doesn't stain.