Algae, corals and other invertebrates,ornamental require an amount sufficient to ensure steady growth calciums natural level of calcium in the sea is about 410mg / l. In marine aquariums, values between 400-450mg of calcium per liter are ideal. therefore should regularly check the level of calcium in your aquarium. This can be done quickly and easily test throughSERA calcium (Ca) Test.sera calcium 1 and calcium 2 can gain easy and safe level of calcium in your marine Reef aquarium .