[Ducks]

I am a retired Electrician out of Local 1 IBEW St Louis/
Metal Halide potential pitfalls/

Metal halides produce great quantities of lumens, and beautiful lighting effects. Used properly by themselves or in concert with fluorescents they are the closely mimic natural lighting for gardens and other systems. My three gripes with metal halides however stand: 1) Their high purchase and operational costs, 2) Safety for your system, home and self, and 3) The fact that full-spectrum fluorescents will give you the quality and quantity of light you want/need for much less cost and danger.Another real concern is the potential for explosion from these 'high-pressure' light sources getting splashed, or otherwise ruptured by inconsistent warming. Keep the lamps, fixtures and shields spotless, and clean them only when cool.

Full-spectrum fluorescents are available in a variety of lengths and wattages in three formats: regular, High-Output (HO), and Very-High-Output (VHO) formats, and compacts. The other-than-regular types require special ballasts, end caps, holders and fixture pins, that burn lamps and phase shift more quickly.

Bulb-Life:for metal-halides is somewhere between 10,000 and 20,000 hours. For loss of spectral integrity and brightness reasons they should be switched out once a year.

Bulb/Fixture Types:

Be aware that there are metal halides, and other lighting modes that have color temperatures of 5,000 Kelvin or less; you don't want these. They are deficient in necessary light in the blue-end part of the light spectrum. However, this limitation can be made up with adding actinic or equivalent fluorescents.

From what I have found to use a light to flower/ High Pressure Sodium works well.

P.S. all this came to me in a Dream while staying in a Motel 6