What color is closest to sunlight ? . . . . White
Many years , metal Halide was used - Color - white. Why- it offered blends of daylight for coral to build sugars for health and food production.
Then came 50/50 - blue was beneficial but white still needed and was kick-off to LED lighting. Then came actinic lighting.
Why does todays light contain white. . . . Preference but still a requirement and should though as I do be run low ( I run at 14%). Ive been running whites almost 4 decades. Look at our members tanks and photography section. . . . all utilize white for their coral
I agree Blue is best primary but to suggest all blue which offers flourescence is complex. by
Dmitry Karpenko :
Before we consider the influence of the light spectrum on coral coloration I would like to point out that even coloration of the same coral may vary significantly depending on conditions. Unfortunately, it is very difficult to provide exactly identical conditions for the corals, even in the same aquarium – and this is even harder for two different tanks. Without providing the right conditions for the corals, other attempts to improve their coloration, such as adjustments of the light spectrum, will be in vain.
Experienced reef keepers well know how variable the coloration of the same coral can be in different conditions. There are three main factors which affect it most: light spectrum and intensity, the amount of food available in water (although coral polyps receive a significant portion of their energy from the zooxanthellae, they are also able to capture food particles from the water column), and from the purity of the water. This last factor is easiest to control: techniques to maintain pristine water in reef aquaria are well known. The second factor, too, can be solved easily since there are a number of quality coral foods readily available on the market. At the same time many aquarists believe that, if there are fish living in a reef aquarium, corals will get sufficient food from small particles which float around from feeding the fish (and fish poo too is consumed by corals).
Light is the last important factor required for good health and the coloration of corals, and yet has not been studied sufficiently well in reef keeping.
The situation is rather complex though, since corals can be very variable, and even the same species may contain different chromoproteins (proteins responsible for coloration) – their type and amount are also determined genetically, in the same way as, say, the color of human’s eyes. Many of these proteins are fluorescent; i.e., they adsorb the light of a certain wavelength and radiate a different wavelength.
