I was able to grow and color SPS, including acros, under LED just fine but I was unhappy that the direct light created too many shadows and the corals did not look good from the front of the tank. I do not agree that LED has issues growing acros.
Maxspect Razor 16K, 100% blue, 80% white.
Top
front
Both the above included a BML strip on the front of the tank angled back to try and reduce the shadowing.
Here it was when i first got it 4 months earlier.
It was doing great until I had phosphate issues and a resulting Alk spike due to slowed growth.
So for this thread my comment would be parameters and stability are MOST important. That and heavy feeding plus good export. I failed the export test. I was not running anything for phosphate removal and skimming too dry. My skimmer was sitting too low in the sump and kept overflowing so I had it set for a very dry skim. I've since raised the skimmer to the proper level, I try to skim so the cup fills up in no more than 2 days, and I'm running GFO to help control phosphates.
I've also switched to T5 due to the shadowing issues but I have yet to achieve the same color or growth I had under the Maxspect Razors ... which I still own just in case.
In my opinion, for what it's worth, if you're running LED, have a look at the coral from the top to see how the colors are doing. If you find the corals look fantastic from the top but are so shadowed in the front so you can't enjoy the colors then think about supplemental lighting, like an LED strip light angled back, or consider one of the other light sources. MH with a tank wide reflector or T5 with a good fixture wide enough to cover the tank front to back.
If you're running LED and having issues with bleaching and no growth then you probably have the whites turned up too high. My other issue with LED is perceived brightness. Because of the nature of LED and the frequency curve you have to turn the whites up too bright for the tank to look bright to the eye. There are plenty of other threads for LED discussions if the color problem is thought to be the lighting. Again, just in my opinion. :beer: