<i>PINPOINT</i>® II Calcium Probe

While there’s a learning curve initially, this provides very consistent, fast and accurate readings. I’ve tested it against an ICP test and it provides a very accurate reading. Rinse in RO water after use, flick off excess water and immediately store in the plastic cap with some moisture still on the tip. Don’t screw the lid on or have the rubber o-ring in tight when calibrating, the tension will cause issues.