I should maybe have specified, sorry. I was talking about "white" in terms of has blue, green and red, like say 3000K-4000K as commonly seen in grow lights...without anything added. I'm afraid we are seeing a lot of what we did in the days of veg and bloom switches.. with everyone copying a trend with no demonstrable reason.
I can tell you from experience that about four years ago I purchased 4x HLG QB324 boards with half Nichia CRI90 and half Nichia CRI80 3000K diodes. These were limited edition boards that HLG discontinued shortly after. What I noticed compared to the 3000K Samsung LM561B strips I was running at the time was that the flowering times were reduced by a few days but the yields were unaffected (and in some cases slightly increased). In other words, I got an effective increase in yield by reducing the flowering times. I noticed this over a number of runs.
I was impressed with these new Nichias and I noted the CRI90 diodes especially had elevated levels of far red. So I went to buy some more QB324s but HLG had sold out. The rest is history: I decided to design my own PCB with Nichia diodes but I also added a little trick I had learned from industrial hemp farmers here in Australia – I added UV diodes (specifically Seoul Semiconductor Sunlike 3030s). And I over-engineered it, because I thought the Quantum Boards of the time were a bit flimsy and the copper circuit left a bit to be desired.
The new design became the original High Light with 450 diodes which was originally intended to be a direct 600W HPS replacement, but I couldn't make a PCB large enough (16" x 16") so I cut it in half and wired two boards together for a 450W "true" full spectrum grow light with 900 diodes that would replace a 600 HPS. Grow Lights Australia was set up a bit later with my partners who believed there was a market for such a board. That's where we are today (I take a back seat to the running of the company, but I'm still very much involved in design and testing).
As for the UV, it all started when a couple of local hemp farmer I knew complained to the government that their crops were reaching high THC levels – exceeding legal thresholds of 0.3% – when grown under Australia's high UV Index sunlight. This was despite the same strains testing under 0.3% in China where the seed stock had originated from. The hemp famers knew all along that UV could raise THC levels and they wanted the government to give them a range to work with so that they did not get caught out sitting on a drug cultivar. So the government raised the threshold from between 0.5% and 1% THC with the stipulation that the seed stock had to test less than 0.5% in the country of origin. So now the hemp farmers had a THC range that took environmental conditions into account.
I had a close look at basic sunlight and noticed that there was much more UVA than UVB, so I wondered if we could get the same results using UVA instead of UVB. Suffice it to say, that's what this thread (and a few others we have started) is all about.
So with due respect, we're not just "copying a trend" – we're setting it. And others are starting to follow. Our lights work and we have the side-by-side tests to prove it.
As for veg and bloom, it might surprise you to learn that we have one light that does both equally as well. There is science (and experience) behind that as well. If you have the right light (spectrum), you don't need separate veg and bloom lights.
