#1 The "Basics", #2 Stability, #3 Lots of Food, #4 Good Nutrient Export
By "The Basics" I mean you meet the equipment requirements of good light and flow. Obviously stability is the most important factor since your acros will die without it and the less stable the system is, the more stressed they will be. Doesn't matter how you keep stability whether it is Kalk or Calcium Acetate, 2-part, Calcium Reactor, tons of water changes, etc.
#3 and #4 go hand-in-hand. Your corals need nutrients to grow - in order to build their skeletons corals use energy and in order to supply that energy, they need nutrients! Carbon, Nitrogen, and Phosphorus are all needed for your corals to convert all your light into energy. Also, SPS have polyps too and like to eat just as much as any LPS does, albeit just smaller particles. Advanced Aquarist not too long ago reported on a study that found acropora grew up to 4x faster when provided with as much baby brine as it could gulp down when compared to non-fed acros. A well fed acro is a happy, colorful, growing acro. Without nutrients and food, you will have very, very pale slow growing acros. And don't forget, fish poop is food for your acros too.
Obviously, with all of this food, you need to make sure your tank can process it and not foul up the water! A good skimmer, maybe GFO if it is need, and regular water changes - that is really all you need for healthy, colorful acros. Obviously there are many ways to skin the nutrient export cat, but as long as you aren't over-stripping the tank of nutrients and keeping your carbon:nitrogen: phosphorus ratio within it's natural range you will be good.
And don't bash LEDs, they work great. I have been using Radion Pros for a year and a half now and my acros look fantastic.