The Aquathin Rust Sentry 2000 Iron Filter with it's powerful "potassium permanganate green sand filtering agent (KMnO4)", actively removes the iron and safely prevents staining. Often, the problem of iron is accompanied by dissolved manganese (blue-green or brown stains) and the rotten egg odor of hydrogen sulfide gasses. The Aquathin Rust Sentry 2000 iron Filter has the capabilities of removing these associated water problems while at the same time, acting on the iron. In areas where water contains decayed organic matter (humic acids or tannins) the Aquathin Rust Sentry 2000 Iron Filter is installed in conjunction with the Aquathin Soft & Clean Water Conditioner to prevent the shadow-type staining associated with tannins.