help with colt coral

[brutherb]

Hi I am new to this forum so please don't jump down my throat because of my ignorance in reef keeping. Any ways My Colt coral is slowly dwindling sway my other piece is doing fine, but the one is slowly discinigrating. I have a 60G tank live sand bed 100 lbs live rock, lighting is power compact, prizm pro skimmer 4 900 gph kyrobi power heads. I water change ever 2 weeks, I dose 5 ml iodide, 5 ml reef complete, 5 ml reef plus, every week feeding 5 ml each every 2nd 3rd day rotifiers and the nanno's