These ion Test strips make water testing fast and easy. Conveniently packed in screw top bottles, the Test papers are safe even in rugged field applications. Obtaining simultaneous pH and ion concentration results couldn't be easier. Simply dip the Test strip in your water sample, wait about 15 seconds for the water to penetrate the strip, and Compare the color changes against the Chart on the bottle's Label. Color-change Test papers give rapid indication of pH level ion presence obtain quick ion concentration measurements in the field or laboratory dip and Compare color change - no calibration, electricity, or warm up needed.