When a decision is made to keep corals and clams, other considerations become important. Because these animals rapidly deplete the calcium, strontium, iodine, magnesium, etc that are measured into most synthetic sea salts, additions or supplements of these ions become necessary for proper coral growth and their overall health. Some aquarists, including myself, choose to achieve this by actually dosing the aquarium with either a liquid or powder-form of these products. There are many marine laboratories such as Kent and Seachem that make these products.
Many hobbyists also choose to use calcium reactors to maintain calcium, alkalinity and pH levels.