True, but it is SO powerful. I have a basic theory that the answer to most any important question in life is usually on a sliding scale of "it depends" to "I don't know." My other theory is that the best-of-the-best understand this paradigm, embrace it and look for the nuance and details to hone in a bit more... whereas and the less-than-the-best pick and choose what they want to find "answers" while not knowing that they are limiting themselves by doing so. Anyway, I had a professor in college say that all science starts as curiosity and anecdotes from experience and observation. Although I might sound crass and like a big-time doocher and make people mad all of the time for saying that actual experience matters, but the post above is kinda what I mean by it. You do not need science to tell folks who used a 6.5K bulb that they are probably a better spectrum for most coral - they lived it even if they cannot explain it like Riddle did a page back... and if they are still in the hobby, they know why they went to bluer light sources over the years. Dana - thank you for what you do and for taking the heat.