Are you using the correct size (#1) Phillips screwdriver? If it's too large or small, then I would expect you to encounter difficulty when you attempt to adjust the screw. Also, depending on the hardness of the screw and somewhat on the "snugness" of the screw in its threaded hole, you could end up damaging the screw head in such a way that it becomes difficult to adjust it with any screwdriver.
Not true. Nichia, RayVio, Sensor Electronic Technology Inc, Violumas, DOWA Electronic Materials Company Ltd., Fotonica (I'm not positive that they manufacture their own, though, as I was only visiting their website to read their rather interesting article on UV-B and cannabis), Osram (was working on it a couple of years ago, but I don't know whether they've brought any products to market yet), possibly OSA Opto Light, Nikkiso might still be producing them, possibly Hongli Zhihui Group Co., Ltd. (I cannot currently access their website), possibly Seoul Viosys, possibly... Well, you get the picture. There seem to be several players.
It's a hot enough subset of the LED market that there was going to be a "Second International Conference on UV LED Technologies & Applications" during the last week of April, but like so many other events this year, it has been cancelled.
LEDs Magazine is a good source of information about new and upcoming LED technology and products, and a great deal of content is posted on its website.
. Also, the rate(?) of response and tolerance seems to vary somewhat.I agree, except for the use of MV lighting in the grow room. I tried that... wow, 30 years ago, lol? I think it tried to kill both me and the plants. Come to think of it, I think I still have that light fixture somewhere, if it didn't get stolen last year. If the thief knew what it was, he probably left it. I probably wouldn't even use an unjacketed metal halide (now), but that's an option.
I've been known to use the reptile type bulbs. That's probably the best bet for the home cannabis grower at this time (and probably the cheapest, too). I've an LED fixture that uses a small tube-type one. It is separately switched, and even has a separate electrical cord so that the gardener can set it up on a different timer than the rest of the light. I like the idea of having it as a completely separate product, though.
I wouldn't mind seeing Mars Hydro produce an UV lighting product - but, again, I would greatly prefer it to be a separate product, in other words, not a general purpose grow light that happens to include UV. Many of us, at least when we use LED grow lighting, will be using more than one (for various reasons). They say that a little UV goes a long way, lol; there's no real reason why it must be included on every grow light in a person's grow space. Also, most of us would not wish to have to purchase all new lighting products if we are already satisfied with what we are currently using. A separate UV product avoids the need to do so.
Ultraviolet light in an indoor garden is useful for more than just growing cannabis. For example, it makes lettuce more colorful and increases its antioxidant content.
