I would agree with the fact that typically simply keeping the pool in balanced and chlorine in there 24/7 with a good filtration system will keep algae away. However, eliminating phosphates from the water isn't a pool store gimic, it does give you some leeway as far as algae is concerned, if you were to slip up and allow the chlorine to drop it will take a lot longer for the algae to bloom. I was at first a skeptic of selling this product however I have plenty of repeat customers with nothing bad to say about it. High phosphate level will also cause a higher chlorine demand in the pool. Furthermore either in the 70's or 80's there was proven a direct link between phosphates and algae growth and laundary detergent manufactureres were required to remove phosphates from their solutions due to algae blooms in the water sources.