With regular use of Reef-Basis Strontium, corals will open more, resist bleaching and resist skeletal rejection better. Continuum recommends that you maintain a strontium level of between 8 and 13 mg/L (ppm), a calcium level of between 410 and 450 mg/L (ppm), an alkalinity level of 7 to 11 dKH (2.5 to 4 meq/L), and a magnesium level of 1250 to 1350 mg/L (ppm).