single treatment lasts 3 months kills black, green, mustard & red algae non-foaming, non-staining formula An essential part of your pool winterizing kit DIRECTIONS FOR USE: Maintain pool water in the pH range of 7.2 to 7.8.  Ensure that the filtration system is working properly and that the filtration system is adequate. A regular brushing program will assist in the removal of stubborn algae. Calculate the volume of algaecide required for your pool. Add the diluted product directly to the pool, distributing over as wide an area as possible. While this product controls algae, it is important that adequate levels of sanitizers (chlorine) be maintained to control bacterial growth.