Check pH and alkalinity before use . Use 5 g (1 level teaspoon) for every 150 L (40 US gallons) to raise pH by about 0.1 pH units (this will also raise alkalinity by about 0.5 meq/L). Dissolve in at least 250 mL (one cup) of freshwater, then add to the tank. The pH of natural sea water is 8.25–8.30. In a well established reef system pH adjustment may be necessary biweekly to semiweekly. Dosing requirements will vary, but do not exceed the recommended dose without checking your pH and alkalinity (alkalinity should not exceed 6 meq/L).