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.