Well...
I need to keep it simple here:
Most of the zoas I've seen in the wild were in very, very shallow waters.
Many were exposed in low tide!!!
The environment that I've found them were closer to, say, the 6500K. As most of us still believe today.
My best growth I had reached in aquariums was using 6500K Ushio MH with NO Actinics.
VHO would be probably better!!
Other than that, natural light with partial sun was also exciting!!!
Today I use T5s and try to get closer to the same spectrum.
It is important to state that the visual spectrum we see in light bulbs is always approx. to what it really represents. Some closer to others, probably. Minimum difference, most of the time...
Other important facts are connected to growth, like water movement and additives.
In regards to the visual preferences, I still like to see in my tanks something closer to what I've seen in nature... around the 6500Ks. My taste.
I don't mind to keep bluer, say 10K or even 14K, but can't hold for long time. Just me.
Shallow water colors rules!!!
Nice "old" thread!!
Very good talk.
Grandis.