They are the essential elements (minerals)that are needed for fish only & reef tanks that appear naturally in the ocean waters and from sunlight. These are removed when there are protien skimmers and UV sterilizers running. They are used by corals, inverts & fish. Many people add them seperately, Strontium, molybdate, potassium, magnesium..ect... I actually add extra iodide for inverts. I had my 55 tank for 7 years, upgraded to a 90 last month and have had a great healthy reef for all 7 years. Much success w/corals & all my fish. The trigger did not kill the clowns. Not a mark as I said. He went in because he was smaller than a 50 cent piece and I was moving him to my 90. I just got him and was acclimating him there since 2 tanks were fed from each other. So the serial trigger theory is not correct.
