All good advice, but there is something wrong here. I kept all my SPS and euphylia just fine for 6 months with crappy 150w CL bulbs/ballasts, using my trusty plastic hydrometer to set my salinity at 1.029. No wilting anything, although my sand did cement together
While I certainly get much better results with bigger better lights, and a now set by refractometer 1.025, I would look at all things, not just the items pointed out so far.
Water source is RO or tap? Good membrane, or old? New tank, or used that could have been treated with copper ever. Using good carbon, or bargain stuff? Using carbon at all?
Really important to test for NO2/NO3/PO4 with these types of issues. What is water change schedule?
And temp, anywhere between 76 and 84, as long as it's stable. Ca, as long as it's over 350, not an issue yet. What is Alk?