Questions regarding RGB Lighting

Nick72

Member
Joined
21 Apr 2020
Messages
172
Location
Kuala Lumpur, Malaysia
I've been very impressed with what I've seen of the new RGB lights from both ADA (Solar RGB) and Chihiros (RGB Vivid 2).

They provide far better colour rendition over all previous LEDs I've seen.

As an example I'm very happy with the growth rates I'm achieving with my single Fluval Plant 3.0 (46W) on a 90x45x45 50 US Gallon tank, but the colour rendition is less than optimum, particularly greens which tend to be yellow and washed out.

Would I buy new lights just to improve colour rendition to please my eye. Yes, I probably would.

So the question. When setting up previous full spectrum LED lights such as the Fluval Plant 3.0, it's common practice to turn the Blue LEDs down to somewhere between 5%-20% (I have mine on 5%) as Blue LEDs really push algae growth.

The whole point of these new RGB 3 in 1 LEDs is to give you full control over the Red, Green and Blue spectrum the lights push out to deliver such eye pleasing colour reproduction, so do you still need to turn the Blue right down?

If not, why not?
 

jaypeecee

Member
Joined
21 Jan 2015
Messages
1,208
Location
Bracknell
Hi @Nick72

You have made an interesting observation about blue light in relation to algae growth. May I suggest you take a look at a couple of threads that I started recently - one was today, in fact. Then, we can pursue the points and question you have raised above. Would that be OK? I'm just trying to get an idea of the light spectrum from your Fluval Plant 3.0. Alternatively, perhaps Fluval provide published spectra? Anyway, here are the threads:

https://www.ukaps.org/forum/threads/free-lighting-tool.60842/

https://www.ukaps.org/forum/threads/i-phos-budget-spectrometer.61076/

JPC
 

Nick72

Member
Joined
21 Apr 2020
Messages
172
Location
Kuala Lumpur, Malaysia
Hi @jaypeecee

I had a look at both of your threads, and downloaded Color Picker.

Though I haven't yet taken the RGB of my light.

Here is what Fluval say about the Plant 3.0

79FD9F0D-5F4F-4A87-8956-26387EF2FF59.png


I don't really understand the above chart as for example yellow on the chart appears to be at roughly 565nm, which makes sense on the visible spectrum.

I don't understand why on the key to the left yellow is somewhere between 6500K to 15000K.

Perhaps I don't understand the relationship between nm and K.
 
Last edited:

Nick72

Member
Joined
21 Apr 2020
Messages
172
Location
Kuala Lumpur, Malaysia
OK. I've read up on nm vs K.

Nm being the visible colour spectrum from 400nm to 750nm.

K being light intensity Kelvin from 1000K to 15000K.

Readings in K are not colour readings but the lights intensity, and a light source of x Kelvin would be made up of of the full spectrum of visible light (nm).

So Fluval putting yellow (or any other colour) on the Kelvin chart is a bit of a nonsense.

Fluval have chosen to put 6. Pink on the Kelvin chart as somewhere above 15000K, where Pink is actually on the high end of the visible light chart below 750nm.

Even far Red ( near infra red) would likely be below 800nm and nm and K have no corolation and are not convertable.

Please let me know if I've got this wrong.

Can anyone explain the scale Fluval are using indicted as 0, 0.5 and 1 on the y axis of there nm chart and titled 'Spectrum'?
 
Last edited:

dw1305

Expert
Joined
7 Apr 2008
Messages
9,995
Location
nr Bath
Hi all,
K being light intensity Kelvin from 1000K to 15000K.
I don't understand why on the key to the left yellow is somewhere between 6500K to 15000K.
The K value is the colour of the light emitted by an elemental iron (Fe) body heated to that temperature (in degrees Kelvin).

planckian-locus-png.png

I'm not sure what it means on the Fluval graph.

cheers Darrel
 

Nick72

Member
Joined
21 Apr 2020
Messages
172
Location
Kuala Lumpur, Malaysia
Hi all,The K value is the colour of the light emitted by an elemental iron (Fe) body heated to that temperature (in degrees Kelvin).

planckian-locus-png.png

I'm not sure what it means on the Fluval graph.

cheers Darrel
So perhaps we are now getting somewhere.

Is it blue on the visible spectrum nm (approx 500nm), or blue on the Kelvin chart (approx 9000K+) that promotes algae growth.

I believe it's Blue on the visible light scale that promotes algae growth.

I don't think going into Blue on the Kelvin scale would make any difference.

To be clear, increased lumen or par would surely increase the chances of algae due to light intensity, but the original post is regarding the dangers of Blue light (eg. Blue on nm scale) to promote algae even at moderate light intensity.
 

dw1305

Expert
Joined
7 Apr 2008
Messages
9,995
Location
nr Bath
Hi all,
I'm not sure any-one really knows whether specific light wavelengths stimulate some photosynthetic organisms more than others. Because we only have one sun, and it is likely that <"photosynthesis only evolved once">, my guess would be that all photosynthetic organisms can make use of the wavelengths of sunlight pretty effectively.
Is it blue on the visible spectrum nm (approx 500nm), or blue on the Kelvin chart (approx 9000K+) that promotes algae growth. I believe it's Blue on the visible light scale that promotes algae growth. I don't think going into Blue on the Kelvin scale would make any difference.
They are sort of the same thing, but measured on different scales.

The <"visible spectrum"> is the range of wavelengths that our <"eyes perceive as colours">. Light is both a wave and particle "photons" , and blue light photons have shorter wavelength, and greater energy, than red light photons etc.

I'll cc in @jaypeecee back in, spectrophotometry is more his field.
but the original post is regarding the dangers of Blue light (eg. Blue on nm scale) to promote algae even at moderate light intensity.
Because blue light has the shortest wavelength it penetrates furthest into clear water and the marine algae that live deepest are the <"Red Algae (Rhodophyta)">, which contain phycoerythrin, a red pigment that absorbs blue light.

Black-beard (Audoinella spp.) and Stagshorn (Compsopogon coeruleus ) algae are <"both Red Algae">, but I think it this point it would be very easy to add two and two together and get five.

<"All photosynthetic organisms contain chlorophyll a">, which has absorption peaks in both blue and red light.

800px-Chlorophyll_ab_spectra-en.svg.png

By Chlorophyll_ab_spectra2.PNG: Daniele Pugliesiderivative work: M0tty - This file was derived from: Chlorophyll ab spectra2.PNG:, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20509583

The "Green Algae" (Chlorophytes) contain exactly the same photosynthetic pigments as all the aquarium plants we want to grow and belong to the same clade (<"Chlorobionta" or "Viridiplantae">), so I'd be pretty sure that they don't differ in their light utilisation from the aquarium plants we want to grow.

f-extant-viridiplantae-green-plants-sensu-lato-png.png


cheers Darrel
 

cbaum86

Member
Joined
24 Jan 2019
Messages
79
Location
Leeds
Here is what Fluval say about the Plant 3.0

79fd9f0d-5f4f-4a87-8956-26387ef2ff59-png.png
The left image you posted from Fluval looks like confusing nonsense to me - not surprised you're not quite sure what's going on.
They're completely different measurement scales and it's weird they've put them on that left side image together.

The graph on the right shows the overall spectrum of the light fitting, but considering you can alter and dim each of the diode colours individually I'm presuming this is at 100%. If you set your own intensity level for each colour you'd have a different spectrum graph - as you note by people setting the blue LEDs to a low %.

The Kelvin, in terms of light fixtures, is the overall hue of the output perceived by your eyes. As Darrel said, the rating is relational to what colour a black body radiator would appear if it were heated to a specific temperature in Kelvin. So heat it to 3000 Kelvin and it would appear a yellow orange, heat it to 8000 Kelvin and it would look more pinky blue.

The measurement of nm is the wavelength of the light, the wavelength represents a specific colour of light. So a blue diode will roughly be around ~460nm and would obviously look really blue to your eye so you may say is around 15,000K. If you added some red diodes they have a wavelength of ~680nm so you'd have a graph with a spike at the blue and red ends, this would look pink/purple and might give you a kelvin of 8,000K.

Whilst you might then say they are linked, and I suppose in a way they are, you could achieve the same kelvin rating with several different spectral curves so you can't have a direct relationship. You can't tell how much of the spectrum is blue because a light has X K rating for example.

But to sum it up, I believe when people say X colour light does this or that for plants, algae etc. they are talking about wavelength.
Kelvin in isolation, apart from how you want your aquarium to look is pretty much marketing so companies can stick another number on the box to sell us something - aesthetics over function.

I believe the Fluval light has white LEDs which have a predominantly blue weighted spectrum because of how LEDs work so you can move the individual blue setting fairly low without affecting the appearance too much. If I were to do that on my Vivid which only has red, blue, green diodes I'd have an orange tank.

🤞I've understood the subject moderately well myself ;)
 

Nick72

Member
Joined
21 Apr 2020
Messages
172
Location
Kuala Lumpur, Malaysia
Thank you all for the above.

I've seen studies on plant (hydroponic - not aquatic) growth under different wave lengths, which suggest that Blue light tends to grow most plants short but full, while Red light tends to grow plants tall but thin.

So I do believe plants can be effected by wave length.

Anecdotally it's said that Blue light in a planted tank will promote algae growth. Note that Fluval's default settings for 'Planted' on the Plant 3.0 set the Blue to just 20%.

So if you accept that the blue light on the Fluval Plant series must be used sparingly to prevent algae growth, what implication does that have for setting up a true RGB light such as the ADA Solar or Chihiros Vivid 2?
 

Geoffrey Rea

Member
Joined
27 May 2017
Messages
754
Location
Cambridgeshire
Blue light has a short wavelength so will penetrate water more readily.... got ya @dw1305 more blue equals “more intensity”!! (Lost In Translation)

1590506507088.jpeg


😂

In all seriousness though the tank above runs 75% white full spectrum LED’s to 25% blue LED’s at 90-100% intensity (200-250 PAR at 30cm depth across most of the footprint) and algae hasn’t been an issue in the last 12 months.
 

Nick72

Member
Joined
21 Apr 2020
Messages
172
Location
Kuala Lumpur, Malaysia
Blue light has a short wavelength so will penetrate water more readily.... got ya @dw1305 more blue equals “more intensity”!! (Lost In Translation)

View attachment 149225

😂

In all seriousness though the tank above runs 75% white full spectrum LED’s to 25% blue LED’s at 90-100% intensity (200-250 PAR at 30cm depth across most of the footprint) and algae hasn’t been an issue in the last 12 months.
That's interesting.

I can't count the number of articles or videos I've seen where enthusiasts have warned against pushing the blue beyond even 15% when using traditional LED lights.

While anecdotal and not scientific I tend to put faith in practitioners, and my own results suggest I get less algae when I keep the blue above 10% (expectation bias?).

So it's very interesting that you can run 25% blue LEDs at near full power without algae issues.

That's leaves me confused.

(I also just noted in your previous post that you say the white lights in the Fluval Plant 3.0 are also emitting heavily in the blue spectrum - I didn't know this. )
 
Last edited:

dw1305

Expert
Joined
7 Apr 2008
Messages
9,995
Location
nr Bath
Hi all,
In all seriousness though the tank above runs 75% white full spectrum LED’s to 25% blue LED’s at 90-100% intensity (200-250 PAR at 30cm depth across most of the footprint) and algae hasn’t been an issue in the last 12 months.
My guess would be that the wavelength of light isn't a major factor in algae growth. <"Taxonomically algae isn't a very useful term">, so I just think of all photosynthetic organisms as "plants", just some are the "plants you want" and some are "plants you don't want". I'm going to start by making conditions suitable for plant growth, I'm not going to worry too much about what those plants are.
Blue light has a short wavelength so will penetrate water more readily.....got ya @dw1305 more blue equals “more intensity”!!
Yes, it is back to the same thing expressed in different ways. From <"Photon energies....">

Figure_30_03_01a.jpg
I've seen studies on plant (hydroponic - not aquatic) growth under different wave lengths, which suggest that Blue light tends to grow most plants short but full, while Red light tends to grow plants tall but thin.

So I do believe plants can be effected by wave length.
Yes, that is right. If you look on hydroponic websites there are various blue and red LED arrays that you can use to grow "Tomatoes"* with differing growth anatomy, dependent upon whether you want your plant as a leaf vegetable or a flowering one. Even though "relative quantum efficiency (RQE) curves" show the highest efficiency is for red/orange wavelengths you need to add in some blue light to get normal growth.

*Other plants may be available

cheers Darrel
 
Last edited:

Geoffrey Rea

Member
Joined
27 May 2017
Messages
754
Location
Cambridgeshire
I can't count the number of articles or videos I've seen where enthusiasts have warned against pushing the blue beyond even 15% when using traditional LED lights.
1590519204387.jpeg

^^^ From Practical Fishkeeping circa 2008

https://www.practicalfishkeeping.co.uk/features/problem-solver-nuisance-algae/

They never cite anything when making claims like the above. The other is using lower K lighting on marine won’t pack the same punch, a consequence not a cause.


I'm not sure any-one really knows whether specific light wavelengths stimulate some photosynthetic organisms more than others. Because we only have one sun, and it is likely that <"photosynthesis only evolved once">, my guess would be that all photosynthetic organisms can make use of the wavelengths of sunlight pretty effectively.
I agree, it also would be an evolutionary disadvantage to be too specific.

Do have to wonder if this simply all began with someone using marine lighting, heavy on the blue and very high PAR, on a freshwater setup and it turned their tank into an algae farm... Then they drew the conclusion that it must be blue light causing this and the idea rolled out from there.

While anecdotal and not scientific I tend to put faith in practitioners, and my own results suggest I get less algae when I keep the blue above 10% (expectation bias?).

So it's very interesting that you can run 25% blue LEDs at near full power without algae issues.
It’ll be more than 25%. A quarter of the LED’s in use are blue, there’s also the blue emitted from the other 75% of white LED’s on top.

Much like your experience I find the Anubias and Bucephalandra are much healthier with more blue in the mix and cope with higher intensity lighting. Can’t explain why though.
 
Last edited:

jaypeecee

Member
Joined
21 Jan 2015
Messages
1,208
Location
Bracknell
But to sum it up, I believe when people say X colour light does this or that for plants, algae etc. they are talking about wavelength.
Hi @cbaum86

Spot on! Of course, it may not be a single wavelength but a band or collection of discrete wavelengths.

With reference to colour temperature in degrees Kelvin, I quite like the material on Wikipedia. I think the animation showing black-body radiance vs. wavelength and Temperature/Source Table are pretty good. This is what I'm talking about:

https://en.wikipedia.org/wiki/Color_temperature

JPC
 

jaypeecee

Member
Joined
21 Jan 2015
Messages
1,208
Location
Bracknell
Hi Folks,

Referring to the Wikipedia link in my previous post, I promise that I didn't contribute the bit that says "In freshwater aquaria, color temperature is generally of concern only for producing a more attractive display.[citation needed] Lights tend to be designed to produce an attractive spectrum, sometimes with secondary attention paid to keeping the plants in the aquaria alive". But, in my opinion, it's making a good point. I might replace the word 'alive' with 'healthy' and add something about algae and cyanobacteria.

JPC
 

sparkyweasel

Member
Joined
30 Jun 2011
Messages
1,226
Do have to wonder if this simply all began with someone using marine lighting, heavy on the blue and very high PAR, on a freshwater setup and it turned their tank into an algae farm... Then they drew the conclusion that it must be blue light causing this and the idea rolled out from there.
That sounds likely. Like a lot of the strange ways of 'cycling' a tank, which seem to have been 'borrowed' from marine use, even though the situation is quite different.
 

sparkyweasel

Member
Joined
30 Jun 2011
Messages
1,226
I agree, it also would be an evolutionary disadvantage to be too specific.
It would. If anything has evolved to need more specific light or other conditions it will be our delicate plants, some of which are found in a particular niche. Many kinds of algae manage to thrive just about anywhere, and 'algae' as a group includes something that can take advatage of just about any conditions except extremely dry.
I don't believe we can provide lighting under which 'higher' plants will thrive but algae cannot survive. If lighting manufacturers want to claim that, I would like to see some actual evidence.
I think the best we can do is to try to get the plants thriving so that they can outcompete the algae, - aim for conditions that are 'good for plants', not 'bad for algae'.
 

jaypeecee

Member
Joined
21 Jan 2015
Messages
1,208
Location
Bracknell
The whole point of these new RGB 3 in 1 LEDs is to give you full control over the Red, Green and Blue spectrum the lights push out to deliver such eye pleasing colour reproduction, so do you still need to turn the Blue right down?

If not, why not?
Hi @Nick72

It would make sense to me that you may need to carefully consider the amount of blue light entering a tank. That's because white LEDs start out life as blue LEDs. This blue light passes through a phosphor inside the body of the LED. The phosphor fluoresces re-emitting white light composed of blue, green and red light in this order of intensity. To this light is then added more blue from the blue emitter in the RGB LED. And this RGB LED also emits green and red light, of course. But, the combination of a white LED and an RGB LED seems to result in more blue light than either green or red light. I'll see if I can dig out some typical spectra to further illustrate the points that I'm trying to communicate in words. But, that's for tomorrow.

JPC
 

Geoffrey Rea

Member
Joined
27 May 2017
Messages
754
Location
Cambridgeshire
It would. If anything has evolved to need more specific light or other conditions it will be our delicate plants, some of which are found in a particular niche.
I think in terms of process. We prevent our plants (weeds really) from reaching the surface constantly. We’re imposing a survival strategy for the plant then expect health. Algae appears alongside organic breakdown... it’s x y or z that caused it. Human beings love assigning causation in place of correlation because it helps underpin a belief structure. Much like nutrition, spectrum is a stick to measure something. It tells you nothing about process. Laugh at it, love it, hate it... the matter becomes how you adequately test it. It’s very difficult to test a process reliably.



If you look on hydroponic websites there are various blue and red LED arrays that you can use to grow "Tomatoes"* with differing growth anatomy, dependent upon whether you want your plant as a leaf vegetable or a flowering one.
Could be off the mark here but to include @dw1305 comments that are probably more useful, I see the difference in growth anatomy to reflect available photon bombardment/spectrum to the plant throughout a season. If varied spectrum does play a role, it will be a signature to a plant as light from the sun passes through the atmosphere at varying angles. Contemporary species of ‘Tomato’ plants are seasonal and grow where light quality will change throughout the season. Would surmise (without any evidence) genes will loosely dictate what a plant will react to according to seasonal growth period in theory and should adapt to conditions. Temperature alone certainly hasn’t fully explained germination rates in my experience with terrestrial species. What about the affect on microbial life and it’s part in the process for instance? Symbiotic life systems seem to have been forgotten here.

Why would applying one perfect spectrum throughout a season replicate the plants natural process? You could argue that equatorial regions where tropical aquatic plants hail from enjoy consistency. But light intensity will change with the rains found in tropical regions. Increased humic conditions will change the amount of organic material in the water of tropical water courses/bodies affecting light penetration.

Growing plants in zero gravity... now there’s where things get interesting.
 

sparkyweasel

Member
Joined
30 Jun 2011
Messages
1,226
Why would applying one perfect spectrum throughout a season replicate the plants natural process? You could argue that equatorial regions where tropical aquatic plants hail from enjoy consistency. But light intensity will change with the rains found in tropical regions. Increased humic conditions will change the amount of organic material in the water of tropical water courses/bodies affecting light penetration.
Also, many of our 'tropical aquarium plants' are not from equatorial regions. Especially some of the old-established favourites; we got Vallis from Italy, Cabomba and Sagittaria from USA and I'm sure there are lots more when I have time to check.
 
Top