Actinic 03 is for aesthetics; it is on the violet end of the spectrum. The "03" really has no meaning. It is simply a marketing term used by the manufacture who 1st developed actinic lighting. I believe it was 1st used for the retail clothing industry.
Actinic 7100 is for photosynthesis; this really helps the growth of your corals. The color is more blue then violet. The "7100" is the Kelvin rating. Some German scientist name something-Kelvin coined this term. Natural sunlight at noon is 5500 Kelvin.
Pure 10K lighting is again for aesthetics, but it does help with photosynthesis. It is balanced sending out wave lengths at all ends of the spectrum. The reason why people consider and use 10K lighting for aesthetics is because if you had only actinic lighting in your tank it would resemble a black-light. Sorda cool at first but you grow tired of it, and it looks like a nightclub.
The color spectrum is ROY G BIV (Red Orange Yellow Green Blue Indigo Violet.) In the ocean, the ROY G end is absorbed in the 1st 10-12 feet of ocean water. Most corals are found between 12-25 feet of the Ocean’s surface. Corals have adapted to use the end of the spectrum which they receive most of. Which is the BIV end. Which is why actinic 7100 is the best light for coral growth.
Glinton, personally I like to use all three of the lights. Aesthetics are important to me, and photosynthesis is important to all of us.
So in summery:
Actinic 03 = The best aesthetics
Actinic 7100 = The best photosynthesis
White 10K = some photosynthesis, and balances the aesthetics look given by the actinics
At least this is how I understand it,
***I don’t want to sound like a Barney Fife, ya know!***
HTH,
B