I don't know about under halides, but I characterize good growth as in my Montipora "capricornis" (probably not the species, but a plating species nonetheless) which I have to frag off every few weeks. Some of the Acropora species I have now have grown from 1/4" to 6+" in about 4 months. I do believe halides could definitely boost this further, but these growth rates are easily achievable with good water conditions and reasonable lighting, anyway.