the biggest things i can stress for really any corals to thrive, but especially SPS, are as follows:
1. having the correct set up for success
2. keeping that set up stable
when things start bleaching, my first thoughts are usually the parameters, especially alkalinity numbers, lighting, and potential disease/pests.
with a T5 fixture i doubt the problem is too much light, could it be too little? where was the coral placed in your tank, what kind of lighting did it come from? T5 are perfectly capable of growing SPS, but you often need to give a little more thought to your placement, since they won't create as much power as deep as MH or LED.
in regards to your alkalinity, or other params, most LPS is pretty forgiving. so when was the last time you tested your alk, what was it, and how are you maintaining it? even relatively small swings in alkalinity can be very detrimental to more sensitive corals. when dialing in my supplements (i've used both kalk and two part) i try to test often, every 24 - 48 hours. once i feel i have a handle on my dosing regimen, i usually dial that back to once a week.
and finally, pests/disease. did you dip or QT the coral in any way? is it possible it would have been sick or harboring some kinds of pests?
oh, and one more thing. sometimes tanks just don't like certain kinds of corals. i have no idea why. my old tank hated montipora digitata and pretty much any kind of sertiapora. i never determined why. for some reason my new tank hates scolys, and acropora digitata, but likes sertiapora and M. digitata just fine. it is infuriating, but likely something i will never unravel.
