# Lets get the 6500k debate going again then



## Danny (13 Feb 2013)

Right lol Since the last sort of debate on what kelvin colour is best I have seen nothing but people saying they are using 6500k, this goes from people new to planted tanks and more experienced guys basically everyone.

What I want to know is why do people choose 6500k? Why not 4000k or 8000k or anything else and why are the tmc tiles 6500k?


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## Ady34 (13 Feb 2013)

colour looks nice  ...
....not too white, not too blue, not too yellow and not too pink, quite good at picking out the colours of both plants and fish.


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## jack-rythm (13 Feb 2013)

It just looks better   simple as  

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## Danny (13 Feb 2013)

So combined with all of that does that kelvin also have the best growth results?


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## andyh (13 Feb 2013)

Whoa massive debate looming.

Me personally 6500 -8000k is best it gives a nice white light and makes greens look vivid. Its what i class as a nice clean white light. Weakness, is the reds, but does this really matter, maybe if you have a shoal of red fish that you want to show the colours off.

4000k is very pink, great for showing reds etc but generally not that popular.

Others will give you a far more scientific answer, but for me visual impact is equally as important.

Example

With a 4-5k tube switched on, you can see the pinkness. was trying to show the red of the plants.

The Rotala Wallichii day 19 by andyh_2011, on Flickr

Same tank Running 6500k (2 tubes) only

White Backrgound by andyh_2011, on Flickr

3 tubes all 6500k

Untitled by andyh_2011, on Flickr


hope this helps


Andyh


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## andyh (13 Feb 2013)

Danny said:


> So combined with all of that does that kelvin also have the best growth results?


My view is, light is light, kelvin is colour temperature. And within the range you are talking about there is no real difference in plant growth.


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## jack-rythm (13 Feb 2013)

Wow! For that specific tank I'm inclined to say the 4-5K works better  

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## Danny (13 Feb 2013)

Wow now that is some difference in red with and without the 4-5k. I think the tank looks much better overall with the mix of 4-5k and 6500k

I am off work and bored as hell so thought this would help pass the time pmsl


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## Ady34 (13 Feb 2013)

Danny said:


> So combined with all of that does that kelvin also have the best growth results?


not sure, many say light is light, but reading a thread in our new sponsors sub forum, they hint at spectoral preference. From what i have read it really makes no difference. I think the 6500K is marketed as most like daylight, but i just pick the one i like the look of and go with that, time and many bulbs has ended up me using something around the 6500 mark, nice and warm and representative.


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## jack-rythm (13 Feb 2013)

I would like to know what brings out more reds in plants and fish, as I'm planning on chilli rasbora and want their colours to be vibrant and strong. Maybe I'll opt for a lower range of Kelvins

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## Ady34 (13 Feb 2013)

Danny said:


> Wow now that is some difference in red with and without the 4-5k. I think the tank looks much better overall with the mix of 4-5k and 6500k
> 
> I am off work and bored as hell so thought this would help pass the time pmsl


i think also the tank layout itself has an influence on what lighting looks good.
An open iwagumi may look too clinical without a hint of red/yellow to warm it up a touch, but jungle type scapes with lots of plants with dense mixed colour foliage and resultant shadows dont need warming up a lot.....of course depending on what your trying to achieve, then the exact opposite may apply.....its all down to personal taste


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## andyh (13 Feb 2013)

Here is simple pic which show the difference well. just took a pic of my t5 luminaire.


Kelvin rating by andyh_2011, on Flickr

As can be easily seen the pink tube is the one with a 4-5k rating the others are 6-8k. I like the versatility of the mutli tube setup as i mix them to give the desired effect.

Albeit i am tempted with a LED after seeing my brothers Marine LED setup and he could change each individual colour level with his IPAD. enhance pinks greens blues etc.

As its already been said different scapes call for different kelvin ratings. I can feel an expensive purchase coming on in the future but right now i can create pretty much all i need with a couple of t5 tubes.

AND just to ADD:
All tubes purchased from Home Page

Top down​1. Osram skywhite 8000k​2. Osram Skywhite 8000k​3. Philips 6500k​4. Grolux 5000k​


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## Ian Holdich (13 Feb 2013)

Kelvin is but a colour choice. Clive made an excellent post a couple of years back regarding kelvins. Ill find it later to save him from having to write it out again.

Remember people, marketing blurb is what you will read regarding spectrums and lumens. Don't believe the hype!


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## Ian Holdich (13 Feb 2013)

post number 11

Cheap ASDA Ikea etc light bulbs | UK Aquatic Plant Society

post number 10

Please look -  good for plants ? | UK Aquatic Plant Society


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## stu_ (13 Feb 2013)

jack-rythm said:


> I would like to know what brings out more reds in plants and fish, as I'm planning on chilli rasbora and want their colours to be vibrant and strong. Maybe I'll opt for a lower range of Kelvins


 
Got a 6500K & a 4000K one of my tanks
The orange colouring on my _T.Hengli _is much better under the 4000K IMO


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## dafil (14 Feb 2013)

andyh said:


> Top down
> 1. Osram skywhite 8500k
> 2. Osram Skywhite 8500k
> 3. Philips 6500k
> 4. Grolux 5000k


In fact Osram Skywhite is 8000K 
Sylvania Grolux is 8500K


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## Ravenswing (14 Feb 2013)

Nothing (?) to do with the original thread, but this might give something to think about Aqua-Web » Onko valon värillä väliä?.  Mainly T8s but even they can give the idea what to look after. One must roll the page down to see pics. I found this very helpfull when learning what Kelvin-rates mean in practice: the spectrum must be seen before tubes or Kelvins are compared to each other and how does the spectrum effects on visual seeing of the light.


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## andyh (14 Feb 2013)

dafil said:


> In fact Osram Skywhite is 8000K
> Sylvania Grolux is 8500K


Changed thanks

Did them from memory, so my mistake.
Are you sure on the grolux? That seems too high


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## greenink (14 Feb 2013)

andyh said:


> Albeit i am tempted with a LED after seeing my brothers Marine LED setup and he could change each individual colour level with his IPAD. enhance pinks greens blues etc.



What does he have? Sounds great


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## dafil (14 Feb 2013)

andyh said:


> Changed thanks
> 
> Did them from memory, so my mistake.
> Are you sure on the grolux? That seems too high


 
http://www.sla.net.au/sites/default/files/SPD%20FL%20-%20GroLux.png


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## roadmaster (14 Feb 2013)

jack-rythm said:


> I would like to know what brings out more reds in plants and fish, as I'm planning on chilli rasbora and want their colours to be vibrant and strong. Maybe I'll opt for a lower range of Kelvins
> 
> Sent from my GT-I9100 using Tapatalk 2


 
8000K makes my cardinal Tetra's color's pop against the green plant's black substrate.


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## sanj (26 Feb 2013)

I think concensus of opinion is not always based on all those opinions having first hand experiance. Most people I would hazard to guess dont actually know.

What a lot of us do know is that plants will grow under many different light Kelvin and the difference in performance is negligible for most of us to notice. So generally speaking you choose what you like the look of.

On my big tank I am currently using a combination of Arcadia bulbs, mostly because I really like the look of their Arcadia Freshwater Pro, which really does give a crisp light where the greens pop. I use these in combination with pinker Original tropical pro and Plant pro which is a combination of the first two. Not the cheapest option. Best go to Lampspecs for that.


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## sciencefiction (2 Mar 2013)

I think when it comes to plants, we should distinguish how we see the light colours and how plants and other animals perceive the light.

Not the best source but here are a few extracts from wikipedia below. Once we understand how we humans see the light, we maybe able to understand what the plants or fish need on another hand which could be something we don't see at all, hence we can't reproduce properly artificially.

_* Color* or *colour* (see spelling differences) is the visual perceptual property corresponding in humans to the categories called red, blue, yellow, green and others. Color derives from the spectrum of light (distribution of light power versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of color are also associated with objects, materials, light sources, etc., based on their physical properties such as light absorption, reflection, or emission spectra._
_ Because perception of color stems from the varying spectral sensitivity of different types of cone cells in the retina to different parts of the spectrum, colors may be defined and quantified by the degree to which they stimulate these cells. These physical or physiological quantifications of color, however, do not fully explain the psychophysical perception of color appearance._

_Electromagnetic radiation is characterized by its wavelength (or frequency) and its intensity. When the wavelength is within the visible spectrum (the range of wavelengths humans can perceive, approximately from 390 nm to 700 nm), it is known as "visible light"._
_Most light sources emit light at many different wavelengths; a source's spectrum is a distribution giving its intensity at each wavelength. Although the spectrum of light arriving at the eye from a given direction determines the color sensation in that direction, there are many more possible spectral combinations than color sensations. In fact, one may formally define a color as a class of spectra that give rise to the same color sensation, although such classes would vary widely among different species, and to a lesser extent among individuals within the same species. In each such class the members are called metamers of the color in question._

_The ability of the human eye to distinguish colors is based upon the varying sensitivity of different cells in the retina to light of different wavelengths. Humans being trichromatic, the retina contains three types of color receptor cells, or cones. One type, relatively distinct from the other two, is most responsive to light that we perceive as blue or blue-violet, with wavelengths around 450 nm; cones of this type are sometimes called short-wavelength cones, S cones, or blue cones. The other two types are closely related genetically and chemically: middle-wavelength cones, M cones, or green cones are most sensitive to light perceived as green, with wavelengths around 540 nm, while the long-wavelength cones, L cones, or red cones, are most sensitive to light we perceive as greenish yellow, with wavelengths around 570  nm._
_Light, no matter how complex its composition of wavelengths, is reduced to three color components by the eye._

_While most humans are trichromatic (having three types of color receptors), many animals, known as tetrachromats, have four types. These include some species of spiders, most marsupials, birds, reptiles, and many species of fish.																																																																																								   _
_Most light sources are mixtures of various wavelengths of light. Many such sources can still effectively produce a spectral color, as the eye cannot distinguish them from single-wavelength sources. For example, most computer displays reproduce the spectral color orange as a combination of red and green light; it appears orange because the red and green are mixed in the right proportions to allow the eye's cones to respond the way they do to the spectral color orange._
_A useful concept in understanding the perceived color of a non-monochromatic light source is the dominant wavelength, which identifies the single wavelength of light that produces a sensation most similar to the light source. Dominant wavelength is roughly akin to hue._
_There are many color perceptions that by definition cannot be pure spectral colors due to desaturation or because they are purples (mixtures of red and violet light, from opposite ends of the spectrum). Some examples of necessarily non-spectral colors are the achromatic colors (black, gray, and white) and colors such as pink, tan, and magenta._
_Two different light spectra that have the same effect on the three color receptors in the human eye will be perceived as the same color. They are metamers of that color. This is exemplified by the white light emitted by fluorescent lamps, which typically has a spectrum of a few narrow bands, while daylight has a continuous spectrum. The human eye cannot tell the difference between such light spectra just by looking into the light source, although reflected colors from objects can look different. (This is often exploited; for example, to make fruit or tomatoes look more intensely red._


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## Mortis (11 Mar 2013)

You know what also makes a difference ? The positioning of the tubes. If the light isnt hitting the viewing side of the fish, it is going to look dull. On my first tank there was just a single 18W 6500k tube in the back half. I had guppies at the time and when they would swim to the front to beg for food they looked horribly dull but when they swam to the back they looked great


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## mi casa (11 Mar 2013)

HI had to jump in i use 6500k only because i don't like the tank looking to yellow as can happen  in the lower k. The water just looks crisper under whiter light but thats just me. My plants are not bothered what light they get as long as it is enough


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