There is one more aspect to the color appearance conversation. The color if the corals we see is affected by two things in our tanks (and in the ocean).
The first is traditional color. Corals absorb or reflect the color of light available to them. A red torch coral absorbs all light but the red, and reflects red light. So to see the true color of the coral we need to provide that wavelength for the torch to reflect it back to us. A broadband white light provides a full spectrum for all the colorful corals to reflect. That part has been said tho.
The second part, that has been missed, is phosphorescence. Certain objects can phosphor or 'glow'. Many corals do this if the right light is available. The right light for phosphorescence is a higher frequency, or shorter wavelength, light. Object that will glow tend to do it at the same wavelength that it's normal color is. Or close to it. A red glow can be fed by any visible or UV
light. A blue glow can only be fed by purple or UV
Taking this into account, by turning down our whites, which decreases the amount of traditional color that is reflected by a coral, leaves the phosphorescence more noticeable to our eyes. It was always there, it was just overpowered, or washed out, by the normal color. The balance between the aesthetic look of the tank and achieving the best growth is a personal one.
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