I personally think metal halides are the best for growth but that's just from my experience! From what I've seen and read most people get great growth from zoas from t5s.
Ive been reading up on vitamin C dosing and think I am going to give it a try since it seems to make zoa's grow and color up like crazy, not to mention it really seems to benefit other corals in the tank
That is such a tough question. I have had all 3 plus PC and VHO... Between water quality, height and genetics... it's tough to tell. Does anyone get better growth when the z/p is stretching for light?
I think placement has to do more with growth than lights. I have 3 tanks all with different lights and it depends were you put it you get great growth. I usually put a frag on each tank if i have space in different locations and if i find the right location anything grows very good. Only difference halide zoos are bigger, led zoos are brighter, and t5 a little of both