Question from a newbie

[an enemy]

I'm new to reefing and as such I know very little about different kinds of lighting. I've seen info on MH and Flourencent lighting but was curious as to why high pressure sodium is not used. Is it the spectrum? amount of light?, quality of light? Again I'm new to this

[davejnz]

Spectrum,HPS generally have a spectrum that has more output towards the middle/red wavelengths.MH bulbs used by hobbyists will have a peak around 420nm(purple)to 450nm(blue) and then smaller peaks throughout the rest of the spectrum.

[dakar]

High Pressure Sodium and Mercury Vapor lamps peak around 3000K, very yellow, meaning they do not produce much light towards the blue end of the spectrum.

Now with that said.... reef tanks using HPS and MV lamps has been done, and still is by at least one person around these parts, and with surprisingly good results.