rikka test kit for measuring pH and KH (carbonate hardness) in marine water.Helps you control water quality and prevent hidden water problems that can harm fish and invertebrates. KH and pH should be tested regularly together with other critical parameters such as calcium (Ca) and magnesium (Mg).Store at 10-25°C in a dry, dark place! Keep out of reach of children!Shelf life: 24 months from the date of manufacture, but no more than 12 months after opening.