so white/blue leds are like a first gen led, and the next gen is a multi-colored or full spectrum led... i do need a light to help support my corals growth
Even just blue and white is perfectly OK as long as there are a range of different blue leds from about 400nm - 480nm and a range of white leds like warm, neutral and cool or 6500K, 10,000K and 14,000K. Back a few years ago led fixtures were just white (and only 1 shade of white... not good at all). Then they stared adding some blue leds (and just one wave length of blue... better, but still far less quality light than it could be).
Now you can do just fine with a blue and white fixture. But you want 2 rules met:
1)
You want a blue to white ratio of at least 2:1 and 3:1 is even better. If it has a 1:1 ratio of blue to white it will work, but it's less than what it could be for the health of your coral.
2) You want a mix of at least 3 different blue spectrum leds. Something in the UV-violet range (400nm-420nm), some in the 430nm-450nm and some in the 460nm-480nm. The mix is less important but I think the 460nm-480nm is a bit less important. It's probably less important to have a mix of white leds, but most fixture have a mix these days. You just want less white than blue. Blue spectrum is 90% for your coral and 10% to make them look cool to your eyes. The white leds are 90% for your eyes and 10% for the coral (they use some of the red spectrum in the white light).
Everybody is jumping on the 'full spectrum' bandwagon and adding red and green leds. IMHO you don't need red and green leds unless your blue to white ratio is at least 3:1 and maybe even 4:1, which nobody offers commercially... yet (but it's coming soon Pacific Sun offers a fixture with no white leds). If you have
very few white leds, you need the red leds (only 2-3%) to get that red spectrum other fixtures get from there over abundance of white leds. The green leds should be set next to the red led and they both should be around blue leds (which should be easy because you'll have a lot of them). The red, green and blue spectrum of the 3 leds will mix and to your eyes it will look white which is good for viewing the corals and making up for the limited number of white leds in a 3:1 or 4:1 fixture. The corals don't see it as white because they don't have our eyes. They see red, green and blue and 2 of the 3 are important to them. The green is there more for us than the coral and keeps the red from making the blue start to look purple to our eyes.
So look for
at least 2:1 blue to white ratio and look for a mix of different blue spectrum leds in the 400nm-480nm range and a mix of whites.
