I wouldn't consider myself a lighting guru but I also have a 55 with an Aquatic life 4 bulb T5 HO
fixture. I run 2 10000k bulbs and 2 actinic and do a 50/50 split. 1 of each in the front and 1 of each in the back. I have mostly soft and LPS
so I don't have a huge light demand but they all seem to do really well under this set up. It also depends how the fixture is wired up. I'm not familiar with how the coral life fixture works. Does it have a timer or 2 power cords?