There seems to be a bit of confusion here about a number of factors concerning this issue which I think we need to distinguish between.
Florescence is the phenomenon where many of our 'neon' colours absorb actinic/royal blue/violet/ultraviolet light and re-emit it at a longer wavelength which their algae can utilize for photosynthesis.
Pigmentation in regards to UV is where corals supposedly produce certain pigments in order to protect themselves from the large amount of UV light they are exposed to in shallow water. (Similar to how we tan). According to what other hobbyists report from certain studies, this phenomena of coral pigmentation has definitively been proven, and disproved. You decide. When this pigmentation phenomenon is discussed, it seems it is usually in regards to UV-B medium wavelength UV light, which in high doses is what can cause things like sunburns to us.
Short wavelength light such as violet light doesn't usually 'look' very bright, as our eyes are not very sensitive to this light, but that doesn't mean the light is not there either.
So it depends upon what you're trying to achieve, whether adding violet light to fill out that missing part of the light spectrum to light your tank for your own preference, if you're trying to make your corals produce pigments to protect themselves against excessive UV-B light, or if you're trying to achieve greater coral florescence by adding light from one of these spectrums. Of course, not all corals floresce, and equally, not all corals (if any) produce UV blocker pigments.
I discussed it this weekend with a well-renowned coral guru, and he said that it'd be just fine to add a bit of UV-A light such as 365 nm LED's in order to really get the florescence to pop. Or a cheaper alternative is to add a fluorescent black light, which produces deep violet light primarily which will get your corals to pop certainly but will make your tank look purple as well of course.
Whether or not true UV light sources actually do produce a significant amount of 'light' is a different matter, which I'm not sure of.
Florescence is the phenomenon where many of our 'neon' colours absorb actinic/royal blue/violet/ultraviolet light and re-emit it at a longer wavelength which their algae can utilize for photosynthesis.
Pigmentation in regards to UV is where corals supposedly produce certain pigments in order to protect themselves from the large amount of UV light they are exposed to in shallow water. (Similar to how we tan). According to what other hobbyists report from certain studies, this phenomena of coral pigmentation has definitively been proven, and disproved. You decide. When this pigmentation phenomenon is discussed, it seems it is usually in regards to UV-B medium wavelength UV light, which in high doses is what can cause things like sunburns to us.
Short wavelength light such as violet light doesn't usually 'look' very bright, as our eyes are not very sensitive to this light, but that doesn't mean the light is not there either.
So it depends upon what you're trying to achieve, whether adding violet light to fill out that missing part of the light spectrum to light your tank for your own preference, if you're trying to make your corals produce pigments to protect themselves against excessive UV-B light, or if you're trying to achieve greater coral florescence by adding light from one of these spectrums. Of course, not all corals floresce, and equally, not all corals (if any) produce UV blocker pigments.
I discussed it this weekend with a well-renowned coral guru, and he said that it'd be just fine to add a bit of UV-A light such as 365 nm LED's in order to really get the florescence to pop. Or a cheaper alternative is to add a fluorescent black light, which produces deep violet light primarily which will get your corals to pop certainly but will make your tank look purple as well of course.
Whether or not true UV light sources actually do produce a significant amount of 'light' is a different matter, which I'm not sure of.
