I think my actual source for that was a "The Grow Show" by "marijuana man" Well, there was a more in depth explanation then "it's just more potent". It was saying something along the lines of this:
Marijuana makes THC glands to fight off harmful UV rays, the more UV the more THC glands. and that MH has more of a UV spectrum than HPS does so that they would infact create more thc glands and a higher potency.
I know to take everything with a grain of salt but it seemed to make sense to me, and was a very in depth explanation of the process broken down the the molecular level.
Marijuana Man's assertion that UV has any effect on THC or resin production simply has no basis in fact.
Mac kicked Google's ass with the
stuff he turned up about UV & cannabis in this post. The results of the best study of the lot are essentially inconclusive.
Be very careful with observational evidence and limited sample sizes. Ice melts down to water, snow melts down to water, everything melts down to water... see?
Scholarly rigour in scientific writing and use of scientific method really does have a lot more value than what someone's friend's uncle's brother-in-law said they once heard about someone doing with tanning bed tubes in their grow op.
I also figured having MH and HPS would help create more overall spectrum coverage for all aspects of the plants growth.
One thing that I don't drive home often enough is that in cannabis growing, 'more' is not always 'better.' More often than not, there's 'not enough, just right and dead' but sometimes there's 'completely unnecessary.'
At no point of the veg or flower cycle does the plant either need nor will use a full spectrum. Light energy is produced at a real cost to you and if the plant isn't using the light, it's wasted money.
Compromise lamps which produce a broad spectrum do so at the expense of maximum intensity. HPS & MH make much greater intensity than broad spectrum compromise lamps like Ceramic Metal Halide because their spectral outputs are limited to only the bands of light the plant will use. A 400HPS makes about 55K lumens with a peaky red-yellow emphasis. A 400CMH makes about 40K lumens but makes a broad, flat spectrum which resembles daylight. In flower, the plant simply won't care much about the extra blue available in CMH but it
will react to the lower intensity by producing less dense flowers.
The only plausible reason to use broad spectrum lighting is if one cannot be bothered to change lamps when changing phase of growth. MH & HPS lighting are available for HPS control gear and switchable control gear can be had as well.
Pairing an MH and an HPS not only confronts the wastage via unused spectrum notion but also the 'lumens don't add' concept.
