I just want to put here what I've said many times, but just for the sake of this thread.
The very best bulbs I've used in terms of growth was the Iwasaki 6500K with some actinic blue tubes.
No bulb will grow corals better than Iwasaki 6500K IMO. The zoas were totally crazy!!!
Color wise the tank looked like a tide pool though.
I had a 55 gal with 2 X 250W Iwasaki bulbs and 2 actinic blue tubes over it back in the day. Hehe!!!
Now... talking about T5s: the very best combo for growth on a 6 bulb fixture IMO would be 3 X 6500K and 3 X Blue Plus bulbs IMO.
Another combo one could try would be: 1 X 65ooK, 1 X Coral Plus, 1 X True Actinic and 3 X Blue Plus or blue Actinic bulbs.
I don't need to grow my zoas fast because they are already growing out of the water!! LOL
I've got 3 X Blue Plus, 2 X Coral Plus and 1 true actinic bulbs and absolutely love it. Perfect growth and original natural pigmentation on the polyps.
There are so many possibilities of combination for T5s!!
That story that most of the corals in the hobby comes from "blue water" isn't a rule at all!!
People can say whatever they want and keep their tanks blue to prevent excess algae growth, but they can't say that they see those corals only in "blue water".
The most amazing coral colors are found in shallower waters!! Part of it is due to protective pigments and proteins, right? So...
Grandis.