# Benefits of violet light?



## Solcielo lawrencia (Dec 30, 2013)

I'm wondering if I should include the 410 violet LED in a light build. It's almost never included in production fixtures. Is the 400-420 wavelength useful for aquatic plants?


----------



## jeffkrol (Jun 5, 2013)

Solcielo lawrencia said:


> I'm wondering if I should include the 410 violet LED in a light build. It's almost never included in production fixtures. Is the 400-420 wavelength useful for aquatic plants?


Certainly "useful", Arguably necessary, possibly detrimental..



> There is no data (figures) to back up PAR results as it is based on theory but we do have a general ideal that to get the best PUR results your lighting would have wavelengths falling between 400 – 550nm and 620 –740nm. (Graph 2)


- See more at: http://www.iquaticsonline.co.uk/blog/what-is-par#sthash.wnZWKQhP.dpufThere

On the above basis, and the fact that FW is "generally" more cost conscience that SW.. including the expensive "effective" violets/UV they are not normally included..


----------



## Solcielo lawrencia (Dec 30, 2013)

So it's really a cost-cutting issue compounded by the fact that violet light is barely visible and adds negligible amounts of light so lower total light output. So a fixture with lower output won't sell as well as a brighter one even if the violet grows plants better.


----------



## FlyingHellFish (Nov 5, 2011)

Dude, you can get a light source that has those areas in mind without it looking all weird and purple. Just get something in the 400nm and something in the 600nm and bang, you're good to go. Also put in higher power white so your tank won't look all funky. You take white, and then you add in what you want. 

Look for a fixture with high CRI, so you get the best colour rending of the plants. You can have any plants looking red/purple if your light source is strong enough, it won't look the same under room lighting though. 

Trust me, purple might look cool for a bit but after while it really hard to look at and enjoy. I turn my colour leds way down.


----------



## Greystoke (Jul 24, 2010)

It's absolutely essential.

Watch this space (somewhat later)


----------



## jeffkrol (Jun 5, 2013)

Solcielo lawrencia said:


> So it's really a cost-cutting issue compounded by the fact that violet light is barely visible and adds negligible amounts of light so lower total light output. So a fixture with lower output won't sell as well as a brighter one even if the violet grows plants better.


well I doubt that they grow plants "better" than say blue light..and yes there "luminosity" is low.... 
I believe their "watt efficiency" (rough reading.. voilets might produce 1W of power out of a 3W led where a blue would give you say 1 1/2W ) is not optimal either, but I do know they are "working" on that..

Back to an example:



> *3W 2Chips Ultra Violet 400nm-405nm UV LED*
> 
> 
> Emitting Colour: Ultra Violet
> ...


$14............for that price I could throw on 5 cool white or royal blue and add a ton more "par" than that one "purple"
I believe some "full spectrum" terrestrial plant lights (and of course reef lights) would include violet/UV as a "part" of the whole..
but somewhat the bottom line is a good "blue" equals 3 or so "violets" in "available energy" for the same photosynthetic systems..

There might be some systems/pigments/hormones that the purple stimulates.. but apparently, from common use, nothing obviously critical..

One possible area seems to be in pigment production as a "protective" mechanism from highly energetic "purple" photons.. but I've never seen any real proof for aquatics, though it may be out there..

for reefers, and if I understand this correctly purple and UV are to stimulate the pigment production in the animal part that is produced to protect the plant part from over stimulation and damage..

something not necessary is FW..

boils down to a personal choice and I know some do it to mimic "full spectrum" sunlight..

As an example.. do we really want to go down that road.. ??? 
http://www.researchgate.net/profile...sorbing_compounds/file/d912f50b0733560f34.pdf


Please note some of this really goes from purple.. to UV-A to UV-b...and each has it's own "effects"..

When dealing w/ LEd's most are vis. purple to a bit in the UV-A range.. Uv-B LED's are quite a specialty and expensive.. I know I blended a bit here.. keep that in mind..but only because there could be a natural blending in a range of wavelengths..


----------



## fearsome (Feb 16, 2013)

I cant speak to violet but I can say that IMO tanks look WAY better with added supplemental lights and I would think violet would add to that. There are 2 reasons. 1 sometimes it reveals colors you have better in something you have. Makes it pop more. The second is that the far red and blue / purple parts of the spectrum don't seem to add a lot to the perceived brightness of the area. I find a lot of tanks to look way to bright up top or even deep into them and almost washed out. Because that is how much light is needed to grow plants. But if you balance the spectrum with more far red or purple / blue you get more output from the light without as much of an increase in perceived brightness. The problem is its pretty hard if even possible to capture this on camera to prove it to the internet. This is why its said you have to see something like a good light in person. 

Cost wise you just get white LEDs so much cheaper. The ray 2 is my least favorite light to look at, but it offers some of the best value for light output.


----------



## FlyingHellFish (Nov 5, 2011)

LEDs, CFL and light spectrum such a heated topic. I say, if it works for you and it looks good in your eyes, then by all means, continue with it. 

I can't stand high blue/purple light, I think 6500K-8000K looks the best. Maybe I just got really powerful LED purple lights.


----------



## jeffkrol (Jun 5, 2013)

From coral research.. You can see a "spike" in photosynthesis @ 420("blue") vs 410 ("UV")
http://www.advancedaquarist.com/2014/5/aafeature

though I do consider the purple/blue range fairly equiv. in the FW world..


----------



## gus6464 (Dec 19, 2011)

Hyper Violet (417-420nm) looks awesome in a reef tank and in freshwater it makes fish colors pop. My last DIY fixture had some hyperv thrown in.


----------



## Solcielo lawrencia (Dec 30, 2013)

jeffkrol said:


> As an example.. do we really want to go down that road.. ???
> http://www.researchgate.net/profile...sorbing_compounds/file/d912f50b0733560f34.pdf


That is NOT an abstract. It's a 5 page summary.



> $14............for that price I could throw on 5 cool white or royal blue and add a ton more "par" than that one "purple"


I'm looking at the output of the violet LED and it's much greater than a single royal blue LED.


----------



## gus6464 (Dec 19, 2011)

Where you buying those violet emitters that cost $14? These are much cheaper.

http://shop.stevesleds.com/3-Watt-Hyper-Violet-Version-10-Clearance-Discontinued-TVDualcore.htm


----------



## jeffkrol (Jun 5, 2013)

gus6464 said:


> Where you buying those violet emitters that cost $14? These are much cheaper.
> 
> http://shop.stevesleds.com/3-Watt-Hyper-Violet-Version-10-Clearance-Discontinued-TVDualcore.htm





http://www.leddna.com/3w-high-power-ultra-violet-400nm-405nm-uv-led/



sorry I suppose I was quite sloppy in my response.. Most was presented to create a discussion not solve one..

"Violet" ranges from 400, 410,430... w/ apparently large price swings (?)

"Royal blue" is 455nm
Depending on the "chart" each has its own conclusion (top 2):


























http://plantsinaction.science.uq.ed...-absorption-and-photosynthetic-action-spectra


Quantum yield between "violet" and "royal blue" would be like .7 (V) vs .65(RB)



> Unfortunately, high quality and efficient violet LEDs are still very expensive and in fact, if installed in sufficient quantity, they account for most part of the LED assembly’s overall cost.


http://www.advancedaquarist.com/2014/4/lighting


----------



## mypc (Mar 13, 2018)

hello,

I just found your forum and registered. It seems like a great place to share plant growth knowledge. 

I'm in a process of building/buying a setup to grow sprouts/micro-greens and your replays would be most welcome. I found a number of companies selling grow lights, but the quality is no there. From my research, it seems vegetable sprouts/greens would benefit from UV and violet lights, exactly what you discuss here.

Would you recommend where do I start, do I need to buy individual LED diodes and assemble myself (is it too technical) or there are pre-build assembles/lights?

Thank you


----------



## jeffkrol (Jun 5, 2013)

Plenty of grow lights w/ "UV" .. Well mostly violet to be more exact..
US starts below 400nm...

UV generaly only aids germination..
Are you referring to increasing plant contents.. i.e pigments ect?


----------



## gus6464 (Dec 19, 2011)

mypc said:


> hello,
> 
> I just found your forum and registered. It seems like a great place to share plant growth knowledge.
> 
> ...


Freshwater folk want their lights to be cheap in cost. Cheap means you won't find violet and UV diodes as they are expensive. Case in point the wholesale cost of just the Luxeon UV diodes on my Philips Coralcare is more than what the avg freshwater person spends on a light.

I have been tempted to contact Luc Vogels from Philips though and ask him about making a diode configuration change on the coralcare for freshwater. It would just need a swap of the giant diode grid.


----------



## jeffkrol (Jun 5, 2013)

Good place to repeat this:

















Really, not much UV does better than just plain blue light...


----------



## SamuelLG (Dec 24, 2017)

Joining the discussion, I was picking some specific leds to make a light fixture for my tank. So, in the last month I was searching in scientific papers about the importance or effect of violet light (mainly 400~430 nm) in plant growth.

It's well known the effectiveness of light from 400 to 700 nm in photosynthesis, and looks like bellow 400 nm (ultraviolet) light is going just to be absorbed by organic matter outside the chloroplasts and generate heat/damage and not contributing to photosynthesis.

So, after checking the absorption of the most important pigments in photosynthesis (chlorophyll A, B and carotenoids) it's possible to see a little absorption peak around 410~420 nm, so violet light *will* contribute to photosynthesis (of course not so much like blue at 450 nm, but it will).












Also, its known that red light will elongate the plants vertically, while blue light (from 400 to 500 nm, what includes the violet range) will make it grow more bushy.

What I also saw was the spectra of some fluorescent T5 lamps sold out there to grow plants in tanks or indoor somehow:





























And surprise surprise, all of them have a little peak around 400~420 nm (violet) along the major peaks in blue (around 450 nm) and red (around 600~700 nm).

So, with all this in hands (or in head), I visited the website SPECTRA to work on some theoretical leds spectra.

I selected the following leds:

CoolWhite (8000K) 3W x 18 units
WarmWhite (3000K) 3W x 12 units
HyperRed (660nm) 3W x 4 units
RoyalBlue (440-460nm) 3W x 2 units

They provide the following spectra, and as you can see, it has blue red and green enough to make it around 7100K. But there is none light in violet part and the website adverts it showing the colored triangles and giving it a score of "78 points".















After that, adding just 3 of the violet leds (Violet (400-410nm) 3W x 3 units) the following spectra is built, which put temperature in the 7500K house, and according to the website, it has a score of "100 points" supplying all the important light wavelengths for chlorophyll A, B and carotenoids.















So, violet leds are indeed more expensive, but I'll give it a try and see how it works providing these additional wavelengths for my plants in my new light fixture. If I change my mind, I can substitute some or all those violet leds by royalblue leds and put the peak at 450nm higher in the spectra (what I don't think is necessary because coolwhite and warmwhite leds provide enough of it).


----------



## mypc (Mar 13, 2018)

Could you guys recommend where to get these LEDs ? Are there pre-build kits available? 

SamuaelLG, you showed an example of a T-5, in general are they more expansive to run vs LED units?

Also SamuelLG, did you buy a system or you are building one yourself?


----------

