Also make sure to feed, feed, and feed your system. Just regular fish food is enough. Try to keep some level of phosphates in your system. 0 is not good for good SPS color as well as too much will not work either. The key is keeping that fine balance. Having an oversized skimmer coupled with heavier feedings has worked very well for me.
I agree with MACH5, feed,feed,feed. My current parameters are Po4 0.015, No3 1. Calcium, alk and mag are stable and have been so for 6 months or so. I feed phyto daily, oyster eggs every other day ( lights out ) and the fish are feed 3 times daily. The skimmer is rated at twice the system volume. I have struggled to get good results, but now it appears that colour and growth are good. Patience and good husbandry will pay off, just dont try to hard, keep it simple!