A general rule of thumb for Mh is 24" x 24" of coverage. Since your tank is 24" tall 175/150w may not be enough. I think 1 - 250w in the middle and multiple T5HO to cover the edges. Keep your SPS in the middle and lay your LPS around the sides? Kind of like a bouquet of roses surrounded by babies breath to accent it. ( I did not just post that, did I? It has been a long week. I need a beer)