YellowOut cleans up algae gently… without those harsh algaecide chemicals that can damage and stain pool surfaces. And it is the only patented, scrub-free pool cleaner available today. Works with chlorine to safely clean your pool unlike toxic algaecides… and does it in just 24 hours. YellowOut is not an algaecide, herbicide or pesticide and does not contain quarternaries (foam), copper (stain), silver or poison. No algaecide can match the safety of this product. YellowOut will not kill algae, however, when used prior to an EPA-registered chlorine, cleanup is achieved quickly and economically.