CrystalClear AlgaeOff utilizes the latest in oxygen technology to remove string algae quickly and efficiently. CrystalClear AlgaeOff is an EPA registered, granular algaecide that works in seconds, adds oxygen to the pond, removes odor. Use this product as needed. For best results use when algae is actively growing. Apply a quarter of a cup for every 25-50 square feet to damp surface and allow to sit before brushing or rinsing off surface.