I'm really interested in fleshing this out. We might want to create a new thread.
At 1 watt each, you are probably going to want 30 - 40 for a 4x4 space. Lets say 40. I actually run 2 40W Fluorescents in a 4x4.
At that number, they are $18.28 each. Just for the star board. so $731.20 not including shipping, driver, assembly, lenses, etc etc.
Unlike most LED manufacturers, there is no expected life listed for these. Normally I would expect 10,000 hours or something similar.
So I am seeing $1000+ and a lot of work to get this in a tent. Then there is the learning curve and plant damage while you are tuning a DIY project.
Here is $200 for a complete kit of (2) 4' florescent tubes and fixtures plus some added goodies:
These fixtures will last years and years. The bulbs 2 - 3 grows. Replacement bulbs are cheap
I see the grower that did this DIY ran 5 LEDs. That does not compute for me with the experience I have using UVB.
I'm not a Solacure fanboy and would love to switch to LED - but I just don't think they are ready yet. I'd much rather spend $200 for a known quantity than $1000 plus a ton of work to find out these LEDs burn out after 2 grows, which is what I am told is the reality with UVB LED today. Thoughts?
Sir, I think you are spot on. Sorry for the late reply, I'm having issues with the notifications here, when I get too many it cuts off the first sent.
To address your post - Yes, I agree
the fluorescent tubes have many advantages over the LED, though I think LED will put out more UVB in radiant flux because it's a monochromatic light as opposed to a minor UVB + UVA + blue & green in which many fluoros have spikes in their SPD.
Some of UVB diodes peak at 285nm where the UVR8 monomer has its absorbance max, so that would make these very efficient.
But, that's so much simplified now on my behalf... - the response plants have towards UVB is actually multifold, some arising from DNA damage, or presence of oxidizing radicals. Plus, the benefits of UVA mediated photorepair.
So the pure UVB diode isnt even a full UV setup. Actually an UVA fluores complemented by UVB diodes could do it.
I never did any cost calculations of hardware as a hobbyist, esp. since these things are in a flux, but I would grossly estimate one would need only a fraction of input power of diode UVB vs the fluoros one - when just comparing the area under the curve of the (UVB) 280-310nm region.
As for the guy doing the 2 grows - he started out with 1 diode but couldn't make out any visible difference and began to doubt the radiative output of the diodes. So he increased diode count and on time to almost full daily light duration and fried all the leaves in direct exposure to these diodes.
It was not really finetuned but at least he arrived at his selfimposed goal/proof. He was also confident on the increases resin both the gentle or the overkill treatment created.
I still have a new medicinal UVB diode here, it has a very low output and peaks at 310nm (a wavelength where DNA damage is still low) and if I manage to find a driver for it will mount it to one of my selfbuild whitelight boosterracks, currently sporting 365, 385, 400, 660 & 730nm diodes. IIRC a study on bean suggested when UVB is sensed the stomatas open wide like in an emergency situation.
However, going overboard with UVB can actually result in an adverse effect, destroying chlorophyll, reducing photosynthesis.
I'll simply have to try that out at some and I actually love to experiment with light colours. If you want create a thread and we could get deeper into the science sharing thoughts and opinions.
Best regards
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