During calibration with the included reagent, midway through the test, the numbers displayed in fusion were the numbers from the bottle. But at the end of the test, it showed very high numbers for calcium and very low for magnesium. Since I only had one cal reagent, I decided to use my own water (tested with Salifert) for calibration. Again...midway through the test, it displayed the numbers I input. But at the end, it showed a calcium of -40ppm. Alk and mag are accurate now. Anyone else have this issue?