Algae are microscopic forms of plant life that can inhabit your pool water. Some algae float in the water, whereas others cling to the sides of your pool. Algae is constantly blown into the pool by wind, dust storms and rain. Without an algae preventer, your water can easily become cloudy, discolored and eventually slimy and smelly. The Ultimate Benefit: Why let algae stand between you and your pool? hth developed the hth Ultimate Algae Guard to prevent algae before it ever starts growing. This long lasting non-foaming algaecide prevents and kills green, yellow & other algae. With one treatment, this product will prevent algae growth in your swimming pool for up to three months. 6-in-1 ActionApply direct to poolNon-foamingPreventative TreatmentRemedial TreatmentTreats all types of algaeSwim immediatelyCompatible with salt systemsCopper free, won't stain surfacesLong lasting 90 day treatment