[Scooterman]

Photosynthetically:
synthesis of chemical compounds with the aid of radiant energy and especially light; especially : formation of carbohydrates from carbon dioxide and a source of hydrogen (as water) in the chlorophyll-containing tissues of plants exposed to light; PAR (Photosynthetically Available Radiation), layman's terms is the useful amount of converted light into useful food source to the corals. MH lighting produces more of this useful light than any of the fluorescents, thus another reason they can grow sps, clams etc, fluorescents would take 1000 lamps to 1MH lamp to get that same amount of PAR rating. That is extreme examples but gets the point through, and even if you had that much more fluorescents, I still don't think they will penetrate as deeply into water as a MH of any wattage, in extreme terms.

Now please don't mis quote me on those extream examples, that is just used to get the point across, not actual values, which would need to be charted.