SPS color question

[Aquattro]

I found this on RC years ago, and thought that it explained SPS color perfectly.

"there are only two things which affect sps coloration. These are zooxanthellae density and accessory pigments.
Accessory pigments are determined by growth, light intensity and spectrum.
growth is also determined by calcium availability, alkalinity, trace elements, flow, temperature, salinity, food and stability. zooxanthellae density is relative to nutrients, growth, temperature and light intensity, spectrum and duration.

when corals exhibit fast growth, the growing margin has fewer zooxanthellae and more accessory pigments leading to colorful tips or rims.
Zooxanthellae can mask colorful pigments when they are in high densities. In nutrient poor conditions and under high light intensity and ideal spectrum, zooxanthellae populations will be further reduced leading to more visible accessory pigments especially within the body of the colony."