canadian1969
Well-Known Member
So couple years ago I recall everyone going through whole UV LED supplementation issue, basically a non starter due to the cost of the UV diodes. I went through some of the older threads on the topic and it seems people are still doing the T5 pure UV or reptile lights.
So I have been searching and have found a few LEDs which might work, they are in a star 3 up package with available optics.
http://www.ledsupply.com/leds/ultra-violet-uv-high-power-led-star
those are just barely UVA @ 400-410nm , ideally we want something under 400nm
https://www.digikey.com/product-detail/en/LZ1-10UB00-00U4/1537-1137-ND/5034037
Those are 390nm and about $5/watt from what I can tell.
Certainly not the ridiculous pricing I see here
So the question now is of total UV that falls to earth 95% is UVA, 5% UVB, so to replicate that I have to figure out the balance . So of sunlight's total irradiance what percentage is UV? I am having a hard time nailing that down. https://en.wikipedia.org/wiki/Sunlight
After reading that, I figure by weight 3-5%, so lets go 5%
Of that 5% , 95% is UVA, so it should break down like this for every 100 watts
95 watts of visible light , 4.75 watts of UVA and 0.25 watts of UVB
If I went with floro I would have to use reptile lights, unless agromax makes 2' lamps which i dont think they do. I would really rather not have a couple CFLs hanging off my new build, just purely aesthetics of course, which brings me to cost.
e.g. 4x4 tent, 400 watts approx , would require 20 watts only of UV. With only 1 watt being UVB.
So I am best trying to replicate what we see outside. Putting the UVB aside for now, we are talking $75 to add UVA to every 100 watts visible. At these levels I am thinking you just leave the UV on all the time.
The UVB is where the thing falls apart. The smaller the wavelength the more costly the emitters become and the less efficient they are. Then I found these
https://www.digikey.com/product-detail/en/rayvio-corporation/RVXE-280-SM-071004/1807-1000-1-ND/7363776
Seems I would have to make my own light strip, but not too bad cost wise. About $8/watt. Going back to a 4x4 space you would need about 5 of these, 4 corners 1 center perhaps 5x 8= $40
The cheapest UVA emitter I could find was
https://www.digikey.com/product-detail/en/lite-on-inc/LTPL-C034UVH385/160-2185TR-ND/5414488
I think you could drive them soft and still get 2 watts each out of them (no?)
So 10 of those @ $8 each = approx $80 ($3.50 for 500, we just need 10 so price is higher)
So if you can build a grow light of 100 watts for $1/watt (ish) to add UVA/B in proportion similar to sunlight would add another $1/watt to the build cost. (not including labour/misc). If my theory holds. This probably would work best in smaller applications 2x2, 3x3 tents at the typical height for a panel 18" or so.
Anyone care to tear this theory apart? At a $1/watt you could build your own mini UV quantum board or light strip easily enough, drivers I would have to figure out, but we aren't talking alot of power. It shouldn't be anywhere near powerful enough to burn the plants, UV sunglasses should be sufficient eye protection and the ability to turn off just the UV components should be sufficient safety.
So I have been searching and have found a few LEDs which might work, they are in a star 3 up package with available optics.
http://www.ledsupply.com/leds/ultra-violet-uv-high-power-led-star
those are just barely UVA @ 400-410nm , ideally we want something under 400nm
https://www.digikey.com/product-detail/en/LZ1-10UB00-00U4/1537-1137-ND/5034037
Those are 390nm and about $5/watt from what I can tell.
Certainly not the ridiculous pricing I see here
So the question now is of total UV that falls to earth 95% is UVA, 5% UVB, so to replicate that I have to figure out the balance . So of sunlight's total irradiance what percentage is UV? I am having a hard time nailing that down. https://en.wikipedia.org/wiki/Sunlight
After reading that, I figure by weight 3-5%, so lets go 5%
Of that 5% , 95% is UVA, so it should break down like this for every 100 watts
95 watts of visible light , 4.75 watts of UVA and 0.25 watts of UVB
If I went with floro I would have to use reptile lights, unless agromax makes 2' lamps which i dont think they do. I would really rather not have a couple CFLs hanging off my new build, just purely aesthetics of course, which brings me to cost.
e.g. 4x4 tent, 400 watts approx , would require 20 watts only of UV. With only 1 watt being UVB.
So I am best trying to replicate what we see outside. Putting the UVB aside for now, we are talking $75 to add UVA to every 100 watts visible. At these levels I am thinking you just leave the UV on all the time.
The UVB is where the thing falls apart. The smaller the wavelength the more costly the emitters become and the less efficient they are. Then I found these
https://www.digikey.com/product-detail/en/rayvio-corporation/RVXE-280-SM-071004/1807-1000-1-ND/7363776
Seems I would have to make my own light strip, but not too bad cost wise. About $8/watt. Going back to a 4x4 space you would need about 5 of these, 4 corners 1 center perhaps 5x 8= $40
The cheapest UVA emitter I could find was
https://www.digikey.com/product-detail/en/lite-on-inc/LTPL-C034UVH385/160-2185TR-ND/5414488
I think you could drive them soft and still get 2 watts each out of them (no?)
So 10 of those @ $8 each = approx $80 ($3.50 for 500, we just need 10 so price is higher)
So if you can build a grow light of 100 watts for $1/watt (ish) to add UVA/B in proportion similar to sunlight would add another $1/watt to the build cost. (not including labour/misc). If my theory holds. This probably would work best in smaller applications 2x2, 3x3 tents at the typical height for a panel 18" or so.
Anyone care to tear this theory apart? At a $1/watt you could build your own mini UV quantum board or light strip easily enough, drivers I would have to figure out, but we aren't talking alot of power. It shouldn't be anywhere near powerful enough to burn the plants, UV sunglasses should be sufficient eye protection and the ability to turn off just the UV components should be sufficient safety.
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