FROG Test Strips are specially formulated for precise reading of low chlorine or bromine levels plus pH and total alkalinity. For use with FROG Mineral Systems that reduce chlorine or bromine use up to 50%*. FROG requires at least 0.5 ppm chlorine while SPA FROG requires at least 1.0 ppm bromine. *Compared to the minimum EPA recommended chlorine level of 1.0 ppm for stabilized swimming pool or the minimum ANSI recommended bromine level of 2.0 ppm for a spa. Note: If water temperature is below 70F, results may read low. Complete color matching within 30 sec.