The majority of daily heat loss is due to evaporation. SolarPill®​ minimizes heat loss by forming an ultra-thin, invisible barrier on the water’s surface to reduce evaporation. Its patented pre-measured delivery system gradually releases the formula into the filtration system to allow for optimum coverage. Replace when necessary to maintain water temperature. SolarPill®​ can be used with all types of sanitizers. For best results, angle the returns downward to decrease water surface movement, as SolarPill®​ is most effective in still water