The Guy is J
ohn Berfelo he isn't exactly a scientist in a real lab but seems to have his stuff togeather the video is here
If you do your research you will see that CMH, MH & HPS have the correct spectrum and then some. They tend to waste 25% of the power used creating spectrum the plant cant use. Simple reason LED's are better is that you can customize the spectrum and lower that 25% loss to almost nothing and just produce a spectrum the plant can use. CMH has better resin production because of the UV-B it produces and you can add a UV-B fixture to your DIY COB setup to cover the UV-B. No clue why the LED manufacturers are not doing this themselves. Closing MY LED troll (not a troll just info but sure someone will disagree). A proper led will use half the power of conventional lights with the same production weight wise and resin wise if you supplement the UV-B somehow. So DIY COB with a UV-B lamp you can equal the production of traditional lights with less heat less power and longer lifespan of the light. LED are not really better than traditional lights per say they are just more efficient so cheaper over the long run and give you the ability to customize the spectrum. I like the idea of the UV-B lamp being separate so i can control it's on time. CMH basically is constantly stressing your plant by literally giving it a sunburn for the duration the light is on. Seems lowering the duration of UV-B exposure during the light cycle would produce less stress and still rase resin production.