keeping light demanding coral under t-5 really does depend on the quality of the fixture , reflector and the bulbs. I can recomend ATI for a fixture and if you are going to go retro overdrive the bulbs with an icecap ballast. This my experience with t5 and keeping sps corals. I know Rex (bigsittingrock) had great results with overdriven t5 and sps on a fairly deep tank. one thing I can tell you for sure... don't go cheap. You will regret it. I have also heard some really positive things on these $300 chinese led fixtures. some very experienced reefers have switched over. hope my long post helps. oh and nems can actually take quiet a bit of time to show ill effects from bad lighting or poor water quality so just to assume it will be fine under any ol t5 because it was alive under pc lights is well an assumption. we all know where assuming can get us.