Hello....so I have been going back and forth on the this for awhile. I am not sure where to have my light. I know there is a few things that go into it but I am trying to learn what I shouldn't do. I have a 125g long it is 73 L 24 H 18 W . I have a 80w 6 bulb ati sunpower....2 blue + 2 coarl + 1 purple + . The light is 4.5 in off the top of the water. My corals range from almost to the surface of the water to almost on the sand bed. I just not sure about coral placement. I have 1 rock with some zoas on it the I have close to the sand bed so about 25in from the light. I also have some hard corals that are about in from the light. I just bought a good size frag from up scales and do not want to see it die on me.