Is light additive (PAR) or are two colors better than one?

[snorvich]

I have a lighting system, Sfiligoi, that allows me to have two metal halide bulbs in the same fixture. The original intent, I think, was to allow two bulbs of different characteristics to cover the same area and get the advantages of two different spectrum distributions. These are SE 400 watt fixtures and ballasts (ACLS ballasts which are electronic and have sunrise, sunset, etc)

What combinations do you think would result in optimum colors for SPS corals and still promote superb growth. For example, maybe Radium 20k for color and maybe reeflux 10k for growth?

Does anyone have thoughts on this? Or is it too much of an out of the way question?

Thanks in advance for any answers!

[Young Frankenstein]

I was thinking of doing the same this week :D Switching between the 175 watts x 2 iwasakis. I want to switch between the 6.5k and the 15k All the threads I have read the 6.5 k is whats the closest to nature for maximum growth and PAR, and the 15k for color and looks. The 15k will be on when I am home in the morning and night.

[snorvich]

Same concept except I would run them concurrently, that is both on at the same time over the same area.

[Young Frankenstein]

To me it sounds like the best idea for maximum results :D