CYA is only available in the middle measurement chamber, therefore it can’t be selected in the left and right chambers. Certain parameters are only measurable within the middle chamber, and thus, can only be selected from the T2 list. The parameters restricted to the middle chamber include:  • 6–CH Calcium Hardness  • 12–CYA Cyanuric Acid  • 22–PPHR Phosphate HR  • 23–POT Potassium  • 24–SULF Sulfate