What chemical is frequently used to prevent scale formation in water systems?

Phosphate is commonly used to prevent scale formation in water systems due to its ability to inhibit the precipitation of calcium and magnesium salts, which are the primary contributors to scale. When phosphate is added to water, it reacts with calcium and magnesium ions, forming soluble complexes that remain in solution, thereby minimizing the deposition of scale on surfaces such as pipes and heat exchangers. This not only helps maintain efficiency in water systems but also prolongs the lifespan of equipment.

Chlorine is primarily used as a disinfectant in water treatment processes rather than for scale prevention. Fluoride is added to water supplies for dental health benefits and does not contribute to scale control. Aluminum sulfate is used as a coagulant in water treatment and can aid in particle removal but is not effective for preventing scale. Thus, phosphate stands out as the most appropriate choice for controlling scale formation in various water systems.