If I remember this correctly- Essential Elements contains, iron, iodine, strontium, magnesium and molybdenum- all of which you can get seperately from Kent. Things that molt (shrimp) need iodine, iron is good for macro algae and supposedly the zooanthella in corals, strontuim and molybdenum are also beneficial to corals, and magnesium helps buffer your alkalinity. All of this stuff is usually in salt mixes, but you might want higher levels depending on the consumers in your tank, and some of it gets stripped out through skimming and certainly by carbon.
I generally add about half the suggested dose of each to my tank on a weekly basis. There are other lines out there as well- NutraSea from Customsealife looks interesting since it contains other viatamins (like C) as well as one that provides spirulina and other stuff for filter feeders.
I don't know about Vicodin, but if my fish would feel as mellow as I do after the breakfast
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, that could be a thought. Ya know what they say..."better living through chemistry" so why not for the fish?