1. Link to pictures hosted on Picasa, Google+, Google Drive, Flickr, Photobucket, etc using the image button

2. Put a pile of Vit C tabs on the steps, and see if there's an effect.

3. Was the 'stain' removed by the trichlor tab?

4. Does the 'stain' brush away?

5. What is your CYA (stabilizer) level?

6. Does pouring an entire bottle of 8% bleach on the steps remove the 'stain'?