Here's a truly informative and very well done piece of research that explicitly tests the effects of light intensity, light wavelength, and other factors on the fluorescent colors of several representative SPS colors (including Acropora, Montipora, and Seriatopora). It's a beautiful study that gets down to the molecular level (monitoring gene expression of fluorescent proteins), with clear results.
Short version for nonspecialists:
- In general, higher light intensity yields more coral fluorescent color (I'll call this "color" below, but technical the findings only apply to fluorescent protein-based color).
- For some SPS, 400 PAR units of light is enough to max out this color.
- For other SPS, 700 PAR units results in more color than 400 PAR units.
- For all SPS tested, blue light yields more color than green light, which yields more color than red light.
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Of course these findings don't apply if you have other color- or health-limiting factors in your tank, like sub-par water quality. Also, many of us know from experience that too much light can result in color loss, so don't think that nuking your SPS will necessarily be better.
Link to the paper:
http://www.int-res.com/articles/meps_oa/m364p097.pdf
-David
