I have looked into using HPS in the past because I have a couple fixtures I got for free. The problem I ran into over and over was that the HPS bulbs do not come in spectrums we want for our tank. Most of the HPS bulbs are really high in the red spectrum (for green houses) which would promote algae, not coral growth.
The same, lack of spectrum, issue occurs with MV bulbs also. Unfortunately manufacturers seem to be more focused to the
MH bulb.
