# 6500 k versus 10000 k?



## oscarsx (Mar 15, 2011)

Don't quote me on this, but I HEARD that 10k bulbs bring out more color in the plants, this might be false... I don't know.

I also would like to get more info on this subject! free bump


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## Erotica Aquatica (Apr 5, 2011)

i would like a little more info from an expert on here, but on my 55 ha have t5 ho lights one 67k and one 10k, running 2 67k was a little too yellow for me, but the 67/10k combination is very bright and makes the colors of my plants come out. Also I dont have any issues with algae, or excessive light on my plants, and I have still experienced moderate growth. 

To my knowledge the more 67k range of a bulb will bring you more growth over a higher kelvin bulb. I would like to hear more about it though.....


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## kevmo911 (Sep 24, 2010)

6500 vs 10000 (assuming the same manufacturer) will bring you no difference in plant growth. Both are within the optimal range for aquatic growth, though different brands have different spectral ranges. The only real difference between the two will be the difference in perception for the human eye. 6500 will have a slightly yellow/red tint, while 10k will have a more blue/white tint. Plants, not having eyes, will react no differently.


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## Ham86 (Apr 22, 2011)

Thanks Kevmo,
If that's the case I'm going to do a 50/50 mix of 6500 and 10000 k. I think it looks good and it's providing a larger spectrum.

Thanks again.


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## shrimpnmoss (Apr 8, 2011)

6700 + 10K looks nice together.


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## jeffro515 (Apr 17, 2011)

Hey Ham. Im not an expert either but my understanding is that the higher blue spectrum will travel deeper into your tank. Thats why 10,000-12,000k are more ideal for coral. The light tends to have to travel further into the tank and coral mainly gets only a blue spectrum in their natural habitat. The red spectrum depletes much quicker as it passes through water. So if your lights are 6500k then they will peak more into the red spectrum and you will have more red and blue waves feeding your plants. But as long as the distance between your lights and plants isnt great, your plants should get a healthy dose of each wave. More dominant blue spectrum will breed bushy slow growth and red will breed fast sparse growth. 

Good luck luck to you Ham86. Keep us posted.


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## ReefkprZ (Aug 21, 2010)

jeffro515 said:


> Hey Ham. Im not an expert either but my understanding is that the higher blue spectrum will travel deeper into your tank. Thats why 10,000-12,000k are more ideal for coral. The light tends to have to travel further into the tank and coral mainly gets only a blue spectrum in their natural habitat. The red spectrum depletes much quicker as it passes through water. So if your lights are 6500k then they will peak more into the red spectrum and you will have more red and blue waves feeding your plants. But as long as the distance between your lights and plants isnt great, your plants should get a healthy dose of each wave. More dominant blue spectrum will breed bushy slow growth and red will breed fast sparse growth.
> 
> Good luck luck to you Ham86. Keep us posted.


from a marine stand point this is fairly accurate except to add: as a point of clarification. 

the 10k 12k bulbs containing less red light are less likely to promote nuiscance algae kelp growth in a marine tank. But to simulate shallow water 0-3 feet deep (tidal zones) in marine water 67k bulbs are used as the depth of water gets deeper, more of the red spectrum gets knocked out, simulating 3-30 feet requires 10k or 12k (all the red and most of the yellow has been knocked out of the water at these depths),green light penetrates all the way down to 150 feet to simulate Deep water 150 feetand beyond blue is needed since ONLY blue light penetrates that deep. which in this case would primarily be actinic bulbs, 420-460 nanometers, which strangely enough is a photosynthetically active wavelength. 

the only time you really have to worry about light spectrum penetration is if your tank is over 3 feet deep. 

for maximum plant growth you want 67k or 55k bulbs since they tend to contain the highest PAR. Par is the measurement of the amount of photosynthetically active wavelengths in light. So the bulb that contains the highest wavelength is going to contain the most wavelengths of photosynthetic light. And here is the surprising part for most people: the best light for promoting fast coral growth is also 67k because it has the most PAR. 

Maximizing par is great up unto the point of photo-saturation after reaching photo-saturation adding more light is superfluous, any photosynthetic plant or algae can only utilize so much light going beyond the amount it needs does nothing more for the plant or algae.

(i'm running off memory here and its 5 am so if I mistyped something don't be shocked)


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## ReefkprZ (Aug 21, 2010)

Ham86 said:


> Thanks Kevmo,
> If that's the case I'm going to do a 50/50 mix of 65000 and 10000 k. I think it looks good and it's providing a larger spectrum.
> 
> Thanks again.


its actually providing a smaller spectrum, or a smaller amount of the complete spectrum, because 65k contains the broadest spectrum, and 10k only contains partial spectrum.

they do look nice together. a lot of times I'll balance out yellow looking light with pure actinic.


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## alexem (Apr 12, 2011)

I have try more lights type and temperature for aquatic plants. It's very important make a good balance for the temperature, because wrong light give a grow chance at some algae.
For my experiences, I try to use temperature like 8000k for single lamp and when i can setup more lights, i use temperature from 6.500 k at 10.000 k .


Natural Aquascaping - Planted Aquarium Blog
www.naturalaquascaping.com


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## OverStocked (May 26, 2007)

shrimpnmoss said:


> 6700 + 10K looks nice together.


Agreed. Each bulb alone is off to me. Together they work well.


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## KrazyFish (Dec 23, 2010)

Hi Ham,

I would go with a mix of each, but let me offer you some advice. I am still pretty new to this hobby but I can tell you first hand that you probably have way too much light.

I was using 4 x 54watt t5ho on my 90 gallon, 3 of which are 6700K one is 10000K. This works out to about 2.25 watts per gallon. I have found that even with pressurized CO2 and a regular dosing regimen this is still way too much for me (I started having algae issues). See Hoppys chart on T5 lighting - these bulbs are very powerful.

If I'm you I would not go beyond 3 bulbs but probably would only use 2 of those.


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## 150EH (Dec 6, 2004)

I don't like the 10k bulbs and they are equal to a cloudy overcast day on the kelvin scale but they will work. I'm currently using all 6,700 and getting very good results at only 1.73 wpg and will be adding some 5,500 bulbs which are equal to early morning sun but I will have them timed so that my wpg doesn't get too high. I think one of the biggest problems you can have is too much lighting and although lighting is very important it can be easily over done.


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## Ham86 (Apr 22, 2011)

Thanks guys,
There is some great advise here. I am a little worried about over lighting, especially as I creep towards 4 watts per gallon. Im gonna try running all four lamps, and I have a pressurized CO2 system and I dose regularly, and work my way down if I start having algae problems.

My old setup had 2x14 and a 1x14 T-5. I installed the new lights when I realized I was getting MUCH better growth under the 2x14 fixture. So far I am crystal clear, and if I notice an algae bloom I have no qualms with reducing the light.


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## 150EH (Dec 6, 2004)

I think you'd be happy at 2.5 wpg.


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## herns (May 6, 2008)

+ 1. 6700k bulb for plants.


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## IWANNAGOFAST (Jan 14, 2008)

I would highly suggest that you only run the 2x24 t5ho bulbs. This is more than enough light to grow any plant.


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## bsmith (Jan 8, 2007)

Actually the 6500k bulb has more green spectrum which the plants can use more of. When compared with a lux (cant remember if that the right one or not) meter the lower k bulbs provided more output.


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## jeffro515 (Apr 17, 2011)

Thanks for helping Bobby(ham86) out. My kid brother is always asking questions. I wish I would of had that much confidence at his age. And access to the internet.


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## audioaficionado (Apr 19, 2011)

I used to think 6500 K lamps were too blue, but now they look about right to my eyes.

If each of your lamps has an individually corded ballast, you can put each one on a separate timer and have a multi lamp midday blast by overlapping the times. Saves the daily hours on each lamp tube and they will last longer.


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## oscarsx (Mar 15, 2011)

Nice.. I guess I'll be buying some 10k bulbs


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## ReefkprZ (Aug 21, 2010)

I totally forgot to mention what I run on my tanks for lights. on my 20 long I run a 10k 420nm (actinic) combo I think it looks great honestly.

on my 125g I run 3 54w x 67k N.O. fluorescent (over-driven) and one actinic 110w vho. (icecap 660-009 ballast)
my 125g is 24 inches from soil to surface. this combination allows me to easily push photosynthetic light all the way down to the substrate. at about 2.17 wpg.


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## Benn (May 10, 2011)

After reading this thread I went out and changed the lights on my 25g to 6700k and 10000k, the combination of the two makes a really nice bright ( but not overpowering) light, it also makes the greens of my swords appear much more vibrant.


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