ya sorry to say, you cant keep acros witht hat light
your montis should be on the top of the rock, and i medium constant flow.
keep your temp, and salinity in line, and IMO 55g tanks are to small for yellow tangs, they need 5' of swimming room, and thats minimum, please slow down on your additions and dont add anymore corals fish, i know its hard, but please let your tank stablize first. and also research everything you want to buy BEfore you even start to save up for it, and alos ask many questions on these forums... many