# 6700k and 10000k lights, how do they look in the tank?



## jesterx626 (Jul 27, 2005)

Do they both give off different colors in a tank? Pix for comparison please?


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## BlackSunshine (Mar 28, 2006)

6700 is softer and more natural. 
10k is very bright and kinda flat spectrum IMO. dosen't really do well to bring color out. compared to other color temps like 9700.


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## harrykaa (Jan 10, 2005)

jesterx626 said:


> Do they both give off different colors in a tank? Pix for comparison please?


Simply yes they do. Human eye sees the 6.700 K almost pure white and usually the 10.000 K (depending on the brand) blueish. But so called plant bulbs or aquarium bulbs (fluorescent bulbs) emit both red and blue light and only little green light, thus they look more like violet coloration.

Color temperature (K value) is defined as the temperature that a perfect electromagnetic radiator (black body) would have to emit light with the same color as the light source in question.
Higher color temperature commonly means more blueish coloration and lower temperature more reddish coloration.
Color temperature is expressed in Kelvins (K). Some examples here.
- incandescent light (2.700 K)
- sun light, blue sky (5.400 K)
- daylight, cloudy (7.000 K)
- sunlight at sea (10.000 K).

Harry










to Tank and Equipment Forum

Harry


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## jesterx626 (Jul 27, 2005)

thanks for the info! for my future planted tank, which light spectrum is the more disireable one? 6700k?


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## BlackSunshine (Mar 28, 2006)

the cora life line of fixtures comes with 6700 and I really like the color it puts in the tank. But some people dig the higher temps because they bring out more of the bright colors in the fish. 
For plants they are good pretty much anywhere in that range. So its really all a point of personal pref of what temps you like best. 
Ive read that Amanos preff is the 9325° K as it is a good balance between the red and blue highlights. however those bulbs are hard to come by. I've only seen them in flourescent's made by GE.

on my planted I have one fixture that has a 36w 10k and a 65w 6700k. 
I love how it lights up.


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## therizman1 (Jan 6, 2006)

I would like to add that the spectrum that the bulb burns at is determined by the manufacturer and there can be HUGE differences in what "10K" bulbs look like depending on who has made them. Personally, I prefer to mix the 2 of them together... I think it really gives it a nice look and makes all the colors look great.


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## rchan11 (May 6, 2004)

the lower the spectrum, the yellower the light. The higher the spectrum, the bluer the light.


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## JustJoshinYa (Mar 25, 2006)

i have two 55W 10k bulbs and a 28W 6700k bulb and the combo looks really nice.


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## jesterx626 (Jul 27, 2005)

anyone have pix so i can tell the difference and see how it actually looks like in the tank?


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## benJii (Feb 17, 2005)

While I don't have any pics, if your running CF's I would reccomend getting a dual daylight 6700/10000k mix. Works great. I saw a link on Reef Central once, they showed the light outputs of all the major metal halide bulbs on the same tank. If I remember right, plants absorb light at about 8000k, depending on the bulb.


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## Ex0dus (Jun 29, 2005)

The color WE see totally depends on the CRI of the bulb.. not the K. Ive seen 6700K bulbs that look yellowish and others that look like a natural sunlight. Basically what im saying is it depends on the bulb as to what it will look like. I use GE T5 bulbs in 6700k w/ a cri of 83, they tend to show a slightly yellowish hue so I balance it out with a 10000k bulb w. a cri of 92 which gives off a pleasant natural look.


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## BlackSunshine (Mar 28, 2006)

Exo makes a good point there. even within the same temp you can get alot of variation. 
take into consideration Acentic bulbs. Altho they are still a 10K light they obviously put out a much different spectrum then a non acentic.

I would get a pic of my tank with either of the lights but I don't think it would be a fair comparison since the 6700 is 2X as bright as the 10K being as the 10k is only 36 watts and the 6700 is 65w.

I tried to take some pics for you to show the diff. but sadly my camera sucks the big one and cannot differentiate between the color spectrums so they all look the same.

Altho the 6700 is more wattage the 10K "seems" brighter.


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## harrykaa (Jan 10, 2005)

BlackSunshine420 said:


> Exo makes a good point there. even within the same temp you can get alot of variation.
> take into consideration Acentic bulbs. Altho they are still a 10K light they obviously put out a much different spectrum then a non acentic.


Of course the CRI (Color Rendering Index) does matter yes, it is basicly a index that shows how well a bulb can show colors of an object. The CRI of sunligth is 100 and usually the CRI of modern fluorescents is about 85-90. It does not vary so much. This means Kelvins are the main factor.

Bulbs (2.700 K) that are meant to be used at home indoors mimic the incandescent bulbs. They do look pretty reddish-yellowish. Plant bulbs look both reddish and blueish because it is the green light that has been suppressed. Fluorescent bulbs are all triphosphor bulbs you see, they emit RGB light (red, green, blue).

The best natural coloration in aquarium and also a good growth for plants can be achieved by using natural white bulbs (6.500-7.500 K).

BlackSunshine420,
you probably meant blue actinic lights. They commonly have a Kelvin value of 16.000-20.000.

Harry


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## BlackSunshine (Mar 28, 2006)

harrykaa said:


> Exo makes a good point there. even within the same temp you can get alot of variation.
> take into consideration Acentic bulbs. Altho they are still a 10K light they obviously put out a much different spectrum then a non acentic.


BlackSunshine420,
you probably meant blue actinic lights. They commonly have a Kelvin value of 16.000-20.000.

Harry
[/quote]

yeah. I always forget the spelling of them. I've had them as low as 10k as well as 50/50s that are in that lower range as well.


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## Coldfire (Aug 20, 2003)

Go to Marinedepot.com to see the comparison between the different K ratings. Of course, this are outputs from Metal Halides (FYI).

There are numerous great points that have been make throughout this thread by everyone. My 2 cents, plants and coral grow better under a lower K light. The lower the K value the higher the PAR (photosynthesis available radiation) which is what really drives the ability of a plant to photosynthesis and grow. It is said that the best growth is achieved under 5,500K lights; however, the higher the K rating the more aesthetically pleasing the light appears to the human eye.

Actinic bulbs are measured in nanometers (420 - 460) not "K".


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## therizman1 (Jan 6, 2006)

jesterx626 said:


> anyone have pix so i can tell the difference and see how it actually looks like in the tank?


IMO a picture of what a tank looks like wont help you... who knows how your colors are set on your computer and a picture can always come out looking different that what it looks like in real life. Best bet is to find people in your area with planted tanks and make friends with them and get to see their tanks and lighting. If you were in MI you would be more than welcome to come see mine as I have a few tanks all with different brands of lights and such... every brand looks different.


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## jesterx626 (Jul 27, 2005)

Coldfire said:


> Go to Marinedepot.com to see the comparison between the different K ratings. Of course, this are outputs from Metal Halides (FYI).
> 
> There are numerous great points that have been make throughout this thread by everyone. My 2 cents, plants and coral grow better under a lower K light. The lower the K value the higher the PAR (photosynthesis available radiation) which is what really drives the ability of a plant to photosynthesis and grow. It is said that the best growth is achieved under 5,500K lights; however, the higher the K rating the more aesthetically pleasing the light appears to the human eye.
> 
> Actinic bulbs are measured in nanometers (420 - 460) not "K".


wow well said, yea i want the plants to grow andddd at the same time, look good in my tank. So what do you guys suggest?


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## DiPpY eGgS (Mar 6, 2005)

5000-6700K is my fav--I would love to try 8000k, but never found any









some prefer the higher k rating though, like in the 9000's or 10000k.


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## Guru (Apr 20, 2004)

6700k bulb mixed with the 9325k GE bulb gives off the best color. The reds stay nice and rich yet don't drown out the green. http://www.aquaticplantcentral.com/forumap...difference.html


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## Coldfire (Aug 20, 2003)

Depends, in FW I like the 50/50 mix with Actinic/10K. On my Reef I have a 14K Halide, but think I will change that to 20K when the bulb needs to be replaced.

Remember that as the "k" value of a bulb increases the intensity (PAR) decreases.


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## jesterx626 (Jul 27, 2005)

Coldfire said:


> Depends, in FW I like the 50/50 mix with Actinic/10K. On my Reef I have a 14K Halide, but think I will change that to 20K when the bulb needs to be replaced.
> 
> Remember that as the "k" value of a bulb increases the intensity (PAR) decreases.


i thought actinic lighting in a fw tank gives you algae? it did to mines.


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## AKSkirmish (Jun 24, 2005)

jesterx626 said:


> Depends, in FW I like the 50/50 mix with Actinic/10K. On my Reef I have a 14K Halide, but think I will change that to 20K when the bulb needs to be replaced.
> 
> Remember that as the "k" value of a bulb increases the intensity (PAR) decreases.


i thought actinic lighting in a fw tank gives you algae? it did to mines.
[/quote]

I dont know about that one-I have been running an actinic lighting combo on my tank for over a year without n e algea problems!!!!!!I love the blue look it gives my tank!!!!!


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## Coldfire (Aug 20, 2003)

jesterx626 said:


> Depends, in FW I like the 50/50 mix with Actinic/10K. On my Reef I have a 14K Halide, but think I will change that to 20K when the bulb needs to be replaced.
> 
> Remember that as the "k" value of a bulb increases the intensity (PAR) decreases.


i thought actinic lighting in a fw tank gives you algae? it did to mines.
[/quote]

If you have a planted tank, then you should not have any algae. The plants should use up all of the nutrients in order to grow; thus, leaving nothing left to fuel algae.


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## jesterx626 (Jul 27, 2005)

yea back then i only had a amazon sword. prolly wasnt absorbing enough as say 50 plants.


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