I think a 10,000k MH emits more uvb than an HPS. My suggestion is that adding blue and/or uvb will increase thc production as i said. The lamp is not the issue. MH or flourescent, sunlamp, or whatever.

...."I've been growing under metal halides (MH) lamps for more than 20 years. In CC issue #34 you stated that MH lamps are useful only when the amber light of a high-pressure sodium (HPS) lamp would cause a problem.
My associates and I would disagree. The consensus among us is that HPS lamps produce more weight, but the stoniest, longest-lasting high comes from metal halide lamps.

Ultra-violet (UV) light is the key. MH lamps produce more than HPS lamps and the more UV, the higher the potency climbs in normally high potency plants. I grow for buzz, not weight, or you could say for love, not money, so the MH lamps suit my purpose. I use a Sunmaster MH lamp. The plants produce a little more weight under them than the old 5500K (Color temperature) bulbs, but they've kept the UV light strong."

Anonymous Bud,
Clifton, Colorado