Lighting is one of the most important components of a reef aquarium. Correct color with the appropriate intensity is a critical factor in the health of aquarium organisms. A combination of LED Blue Actinic, and White 10K White LEDs creates approximately 18,000-degree K and are what many aquarium hobbyists consider the most pleasing, not only for the tank inhabitants, but also for viewing pleasures. Using this light will provide the appropriate 50/50 range of both blue and white light.
Actinic is blue... more precisely Actinic is the FAR blue range
The first line in WIKIPEDIA
"Actinic light is either light that affects photographic film, or will facilitate photosynthesis or stimulate light sensitive species
A wavelength of approximately 410 to 465 nanometers (nm), are the wavelengths where photosynthetic efficiency in relation to corals is at its highest.
Design specifications subject to slightly change as new technologies are developed.