Some queries on Metal Halide and PL lamp

I suppose that metal halide lamp give out better light intensity and is more efficient than that of PL lamp. True?

I came across some info stating that the green water created by MH and Pl lamp is different, is this true? And if i could recalled correctly, the green water created by MH is closer to that created by naturally sunlight, true?

Also, how does UV contribute (negatively/positively) to green water?

If all the above have been addressed, pls kindly direct me to the respective source.

Thanx in advance!!!