420nm will not grow corals betters and is just throwing light in your tank you can't see well. Also, violet LEDs, especially cheap ones are horribly inefficient. You could replace *all* the lights on your rig with 400-420nm and nothing will grow better but your tank will look darker.
Also, LEDs above 6500k or so are silly. The difference between a 6000k, 10000k and 20000k LED is the first one has a bit more green and orange in it. The amount of blue light is about the same...maybe a tad more in the higher kelvin LEDs because the phosphors are thinner.
I'm modified many MARs aqua units. The biggest problem is they have too many white LEDs so when cranked up your tank is too green / yellow.
What you want to do is make one entire channel blue and half the other channel blue. The remaining half of one channel should be a 50/50 mix of warm white or red and a few cool whites. Ditch greens. Thank me later.
One trick with a MARs aqua to test colors without destroying it is get a roll of electrical tape and cut 1" squares and put them over the lenses to test various color balances. What you'll find is you end up covering up most of the white ones and the greens to make it look good.
I also strongly recommend keeping both the 450nm and 460nm LEDs on the blue channel. The 460nm (sljghtly more windex looking color) helps mitigate the purplish tone of 450nm blue and gives more depth to colors.
That is a good idea about the electrical tape and I am going to try that. Do you have any pictures, etc of the layouts you used? Also, I thought 420-460 was an intricate part of SPS growth. These are the spectrums ATI Blue+ T5s hit hard.







