420 nm or 460nm?

Do corals benefit more from 420nm (Super Actinic) or 460nm (Blue Actinic)? I was looking at Sanjay's spectral plots of 250 watt DE bulbs and noticed that the Phoenix 14K peaks higher at 460nm which shows why the bulbs appear so blue and the Giesemann 14.5K coral bulb peaks higher at 420nm. Which color will benefit corals more or are they equal?

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420nm True actinic, 460nm is Actinic blue. If you want your corals to have the almost black light effect, go with 420nm, it will really make the colors stand out. 460nm will to, but nowhere near as much. Its all for aesthetics
anyways. IMO, you are dealing a reef tank and not the ocean. If you are trying to simulate the ocean in the same depth of your tank, then 6,500K is what you need. Excellent coral growth, but bland colors as all natural reefs in shallow water. The deeper you go in the ocean, the bluer the water because light doesn't penetrate as much and appears bluer. So the coral colors look better then in shallow water.

If you're going by what sanjay used in his tests, then you need to have the same set up as he did to get the same results. Different tanks=different results. What works great for me, might be horrible for you. There is endless varibles in any tests and not all varibles are tested.

 

I agree with geek and just to add to what he touched on with regards to the light issue...water is a strong filter! Taking the sun's light spectrum, at the water's surface all light waves are evident. Within 15' the spectrum has been altered as the red and orange wavelengths have been filtered out. By 10', yellow light is gone. At 50', the gree wavelength is gone leaving just blue and violet rays(wavelengths) thus the natural blue color of our oceans!

As for the 420 or 460nm bulb coloration, I wouldn't think that it would make much difference, other than the aestetic appeal to you. The fluorescing characteristics will be evident with both.