# do any of the color-changing rgb leds actually produce good light?



## jeffkrol (Jun 5, 2013)

Yes and no, intensity is quite low due to the "type" of diode and of course many missing spctral bandwidths w/ known and unknown actions..
In other words not ideal but w/ enough of them they can grow stuff..

Besides the RGB "white" produced is unappealing to many..


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## kaytlu (Jun 18, 2015)

I was interested mainly in the led strips for planted tanks which have "dedicated" white leds with interspersed rgb leds which can be adjusted to whatever color (kind of) you wish.

(I was looking at the water reflection of these rgb leds during the following) 

If you start at a complete color max, say blue, and then press the plus button for the desired added color, say red, the led in this example produces just a dot of red surrounded by blue, which then grows in size (repeated punching of + key) until it is finally the only color showing.

This is a cute trick, and you can fine tune it to get just the color profile you want, but I'm wondering how much of that color is actually supplying the correspondingly correct wavelengths for plants.

So, is it just eyecandy for humans, or does it benefit plants?


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## jeffkrol (Jun 5, 2013)

kaytlu said:


> I was interested mainly in the led strips for planted tanks which have "dedicated" white leds with interspersed rgb leds which can be adjusted to whatever color (kind of) you wish.
> 
> (I was looking at the water reflection of these rgb leds during the following)
> 
> ...


Any visible light photon is useable by plants.
Green just not as much.. 


as to the tricks.. yes one of the main purposes of the colors is for visual appeal..


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## Solcielo lawrencia (Dec 30, 2013)

Fluorescent mercury vapor lamps have multiple spectral emissions, not unlike RGB LEDs. They grow plants just fine, though the spectrum isn't ideal. White LEDs are superior.


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## kaytlu (Jun 18, 2015)

Thanx,

Just wondering, since so many manufacturers make use of these. Others however make a point of telling you that the colored leds in their products emit in the mostvalued (forplantfrequencies therfore are a "true" red for instance.

Apparently, the human eye simply ignores that kind of differentiation. Probably because we don't eat light ( I wish!) ...

So, I guess it's a judgement call. On the one hand you've got a light that can be fine tused to just the effect you like, within reason, but about a third or more of the strip produces quite inferior light, vs. a light that's better for the plants, but not as easy on the eye.

Surely it would be possible to have a changeable rgb that is calibrated to the correct frequencies? So that,for instance, when You hit the optimal "grow light" combination a light on your panel would Flash, or beeP, or buzz, or confetti fall out of the sky or _something _!

I HATE this stupid galaxy tab's insistence on changing what I write into what it *thinks* I should say! I make enough errors on my own, without having to fight some idiot tablet's programming


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## roadmaster (Nov 5, 2009)

jeffkrol said:


> Any visible light photon is useable by plants.
> Green just not as much..
> 
> 
> as to the tricks.. yes one of the main purposes of the colors is for visual appeal..


 
+one^


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## austin1 (Oct 30, 2014)

My understanding is that white led's are actually blue led's with a phosphorus based coating that makes it visibly white, white led's dont technically exist. The "white" led's you see for sale have the same spectral emission as the blue led used to make the fixture prior to phosphor coating. An rgb fixture can also be used to generate white light, r+b+g=white. This results in a broader spectrum than phosphor coated blue led alone, at least that's the conclusion I have drawn and logically it makes sense. The green light on the rgb contributes to the "white" light look so it's benefit is basically limited to visual pleasure (if you like white light). So if you have a fixture that's 36 watts with even numbers of rgb 3watt led's then you only have 24 watts of the more beneficial red and blue spectrums (12 each, as noted above some of the green gets used by the plants though too), vs a fixture of phosphor coated blue led's with the same power giving you all 36 watts of blue spectrum for plant growth.

Both will grow plants, you might need a little more power with the rgb depending on the bulb and tank dimensions. But the rgb also give you a ton of fun and enjoyable effects options.

That's my two cents for what its worth.

Thanks


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## jeffkrol (Jun 5, 2013)

austin1 said:


> . An rgb fixture can also be used to generate white light, r+b+g=white. This results in a broader spectrum than phosphor coated blue led alone,
> 
> 
> Thanks


actually it is a bit the opposite depending on "what white" LED.









Vero:


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## austin1 (Oct 30, 2014)

Interesting, that due to the coatings then? That makes sense though I guess I was only thinking about cool white leds that I mostly use.


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## jeffkrol (Jun 5, 2013)

austin1 said:


> Interesting, that due to the coatings then? That makes sense though I guess I was only thinking about cool white leds that I mostly use.


A mixture of cw and ww pretty much covers everything except cyan and "purple"..
660nm red can still be a little weak though.


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