Pool Check Copper 3in1 is the world's first test strip designed to measure Copper sanitizer levels used in alternative sanitizing systems. Combined with pH and Total Alkalinity readings, Pool Check Copper 3in1 satisfies your testing needs where others fall short. Simply dip one test strip into your pool or spa for 5 seconds with a gentle back-and-forth motion. Remove the strip and shake once, briskly to remove excess water. Wait 15 seconds and match with the closest colors.