[header] How to diagnose and remove any swimming pool stain [title] Look at the color of your pool stain to classify the cause. [step] There are various stain colors that commonly appear in pools, and identifying yours will lead you in the right direction for treatment. Depending on the cause of the stain, you will need a unique removal plan. 
[substeps] The two main stain categories are metal and organic based stains, which come in a variety of colors. These color combinations include green-brown, red-blue, blue-green-black, green-brown-red, pinkish-red, or brown-black-purple.