The disadvantage of artificial seawater is that after raising fish for a period of time, because fish and other organisms continue to absorb trace elements, the trace elements in the seawater will be lacking. If it is not supplemented, the fish will become rickets, lose appetite, slow to respond, weaken, and get sick easily. Therefore, the water should be changed regularly and the appropriate amount of trace elements should be added. This is the biggest difference between artificial seawater and natural seawater in the ocean. There are different kinds of trace element additives on the market today, which can effectively prevent seawater aging. Some additives contain molybdenum and rubidium, which are more effective elements for algae and mollusks, and help promote their growth.