Hi Joel,
you and I have almost the same systems
Have you always had problems with SPS coloration or are you thinking that they should be coloring up with the use of zeovit?? I have been using zeovit for about 6 months now and my corals are nice but not like the photos of other zeovit tanks.
Anyways here is what I dose for zeovit for comparison sakes:
zeobak 4 drops 2x week
zeofood7 4 drops 2x week
coral vitalizer 4 drops 3x week
zeostart2 0.3ml 2x day
coral snow 2-3mls 3x week
If I were you I'd cut back a bit on your coral vitalizer, sometimes too much can darken tissue as well as the amino acids (as per zeovit.com). If you've just started with zeovit I'd stop the amino acids altogether and wait until you have run the system for awhile before adding that (thats what I was told on zeovit.com).
I'd also think about maybe increasing your halide photoperiod to 10 hours a day? The XM 20K aren't really providing a ton of light but thats just my opinion.
As for the iron supplements, you haven't indicated that you are using any?? I doubt the caulerpa will cause you any problems. I think the taxifolia is one of the safer caulerpas to use for nutrient export.