Foundation Elements – It’s all in the balance. A successful coral reef aquarium is dependent upon maintaining the appropriate water parameters that, in turn, provide the stable environment required by the corals. Although all the elements found in natural seawater have an important role in providing the optimal water parameters, a few of them have a more significant role in the overall stability. These elements are the foundation of the reef environment and they include the three major elements: calcium (Ca), magnesium (Mg) and bicarbonates (HCO3). These three reef foundation elements have a major effect on the water chemistry (pH stability, alkalinity and seawater ionic strength) and on many of the coral’s biological processes (skeleton formation, ions exchange and photosynthesis).