Phosphorous is very significant with regard to the metabolic processes of many different types of plant life. Specifically, it plays an important role in photosynthesis and respiration. However, the optimum phosphorous requirement varies widely between algae species. Because there are over 7,000 species of green algae, it would be difficult to predict the minimum phosphorous level required for a specific type of algae that may exist in a particular pool. In addition, it has been determined that most algae have the ability to store phosphorous within their cells. This is known as “luxury phosphorous uptake”. This means that algae can continue to grow even in a phosphorous-deficient environment. This is just another defense mechanism that algae have to help them survive.
The addition of nutrients, including phosphorous, to a lake or pond may increase algae growth and therefore disrupt the balance of the ecosystem. The EPA puts limits for discharge of nutrient-containing water into lakes and streams so as not to upset this balance. Because a pool environment is completely different, the same limits do not apply. A pool environment includes filtration as well as the use of sanitizers and algicides which are toxic not only to algae, but to other aquatic life as well. In addition, industry standards such as APSP-11 (for commercial pools) and APSP-5 (for residential pools) have no restrictions on the amount of phosphate in pool water.
The growth of algae will be effected by the presence of sanitizer and/or algicide. For example, hypochlorous acid will enter the cell wall of bacteria or algae and disrupt metabolic activity. With metabolic activity being disrupted, growth cannot continue even in nutrient-rich surroundings. It is important to choose products for algae treatment or prevention that have been registered by the U.S. Environmental Protection Agency (EPA). EPA registration is a rigorous process that requires the submission of supporting data. Compounds that currently carry EPA registration for algae treatment include hypochlorous acid, hypobromous acid, ammonium chloride quats, polyquats, copper and silver.