What causes Florescent green pigment

[KingCow]

I have a 120 Gal system consisting mostly of Acros, millis , and stags. All the coral appear in good health, I have what i believe is good growth and base encrusting. Nearly half of my SPS develop some hue of green florescent pigment.

Is lighting the culprit as the coral are producing the pigment as a form of sunscreen? I have 2 360we Kessils tuned at 45% color and 80% intensity. I also have 4 ATI 54 watt T5 bulbs. 2 Blue+ 1 Purple+ 1 Coral. The lights sit 10" above the water surface. I ramp the lights up and down with a 6.5 hour peak.

All the corals are placed between 280 - 360 Par range Per Apogee par meter.

 

[Ron Reefman]

Many corals, from zoas to softies to lps and sps develop pigments that fluoresce under blue and some UV light. And yes, it is a reaction to the spectrum of light it gets during the day. It's somewhat like a sun screen or what humans get when they go out in the sun and turn either tan or red!

It's not just green that should get fluoresced, every color except blue and violet are possible. My tank looks like a 1960's hippi poster under a black light when just my blue leds are on. It's especially great looking if the room is dark.

The reason violet and blue don't fluoresce is because the pigment is using the energy from the blue light of the leds. It has to take a bit of that energy to fluoresce the colors so blue is almost impossible and violet is even harder.

Some say true UV (less than 400nm wavelength) will cause even more fluorescence, but when I tried a 380nm UV the only color to fluoresce was green. And I have about 60 different corals that fluoresce all kinds of colors under violet and blue leds.

 

[zachfishman]

Two major reasons for coral fluorescence: a "sunscreen" effect and/or a way to photosynthesize more wavelengths of light by re-emitting certain wavelengths of light as different, useable wavelengths. Check out this article at NG:

http://news.nationalgeographic.com/2015/06/150629-glowing-fluorescent-corals-science/