Phosphates are compounds of the non-metallic element phosphorous. They are the primary food source for algae. When phosphates are present in your pool at any given time and any form of algae is present, whether visible or not, the algae will feed off the phosphates and begin to grow rapidly. Unfortunately, phosphates are everywhere surrounding pools and it can be introduced in so many ways. It is found in dirt, leaves, garden fertilizers, lawns, lotions, detergents, other type of chemicals, shampoo’s, and municipal water. The wind, rain water runoff, and swimmers are all culprits in introducing this into the pool.
The way phosphates affect the pool is by decreasing the disinfection rate (kill rate) of the sanitation (chlorine) which typically lowers the potency of the sanitation allowing the growth of the algae to bloom at a faster rate. Chlorine is measured in Parts Per Million (ppm) while Phosphates are measured in Parts Per BILLION. Allowing phosphates to grow without being treated will always result to more frequent outbreaks of algae.