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Hey Clarence... It's VERY hard to tell the difference between a 440nm and 460nm (you mentioned 420nm - there are no LEDs of 420nm in these fixtures. 420nm is very purple, and doesn't put out enough lumen for coral growth). BUT, there is a difference when filtered by the water column. Looking directly at the LED isn't going to show you that difference in spectrum, but the glow in your tank will. Glad to hear they are working great!!