Stable water chemistry is the backbone of a healthy reef. Corals and invertebrates do best when temperature, salinity, alkalinity, calcium, and magnesium stay in a tight band day after day — sudden swings are harder on livestock than sitting a little off an “ideal” number. Use the chart below as a practical starting point for a mixed reef, test regularly, and change one thing at a time.

Need to dose or mix salt? Try our Reef Calculators.