The Importance of Kelvin Spectrum
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Old 08-25-2011, 02:45 PM   #1
sAroock
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The Importance of Kelvin Spectrum


Hi,
Im using x4 T5 lighting with Kelvins of 14000K and Sylvania Gro-Lux 8500K.
This is out of range isnt? I read 5500K-6500K midday sunlight thus the recommended range. Is it important to keep it within range?

Are theses K's contributing to my poor results?
(cuz i got EI and Co2 covered).
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Old 08-25-2011, 03:24 PM   #2
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It might not be the optimal spectrum for freshwater plants. Then again, it might be -- emitters with the same color temperature can have quite different spectrums so color temperature--while elegant--isn't a particularly good metric. But I doubt this is your problem provided that intensity is adequate. Your plants will use any light they get, they're just a bit more efficient at it at certain wavelengths. They may end up a bit shorter and bushier than if they had more red in their spectrum, but you may end up preferring that. For a neat demonstration of the opposite effect, try to grow some plants under a household incandescent bulb...

OTOH if you're having a lot of algae issues, your light could be a factor. There is plenty of anecdotal evidence that algae is better at using light at wonky wavelengths than plants. I've never experienced this myself, but I've heard it on the internet so it must be true.
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Old 08-25-2011, 03:44 PM   #3
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More often than not Co2 is no where near where you think it is. K rating is is related to visual spectrum and the actual output of the bulbs vary so much it is almost impossible to tell.

Lots of people grow great looking plants with bulbs with those K ratings... but since it is so subjective it means next to nothing.

OLD bulbs are often a problem too. Hard water causes more problems than most people think, too.


TOO MUCH light, Too LITTLE co2 and too little nutrients are usually the issue.
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Old 08-25-2011, 03:49 PM   #4
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I'm not looking for optimum plant growth. I'm trying to create a tank that I like to look at. That said, I'm not fond of the overly yellowish look that using all 6,700k bulbs gives.
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Old 08-25-2011, 03:50 PM   #5
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Quote:
Originally Posted by fresh.salty View Post
I'm not looking for optimum plant growth. I'm trying to create a tank that I like to look at. That said, I'm not fond of the overly yellowish look that using all 6,700k bulbs gives.
Then an 8000-10000k bulb is prob more suitable for you. Plant growth is fine as well.

Sometimes mixing the K ratings to get what you want is necessary.
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Old 08-25-2011, 04:39 PM   #6
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Quote:
Originally Posted by OverStocked View Post
More often than not Co2 is no where near where you think it is. K rating is is related to visual spectrum and the actual output of the bulbs vary so much it is almost impossible to tell.

Lots of people grow great looking plants with bulbs with those K ratings... but since it is so subjective it means next to nothing.

OLD bulbs are often a problem too. Hard water causes more problems than most people think, too.


TOO MUCH light, Too LITTLE co2 and too little nutrients are usually the issue.

100% agreed with Overstock.

Nearly every "white" light that we might use will grow plants. The 6500K range is "optimal" but only critical if you are using a low light level, where every photon must count lol.


Nowadays with light sources as efficient as we have, you really don't have to fret it. As long as it's white (or even blue or red) it will grow plants as long it's not 100% blue or red. And even then, pure red or blue might grow a surprising number of plants.


I use a mixture of white, blue, and red LEDs (very few reds, they are overpowering if used too much). My tank's color temp is way way way cooler than 6500K. I have no way of measuring it but it's easily 10,000K or higher. Looks lovely and I can change the color temp with the twist of a dimmer knob.
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Old 08-25-2011, 05:03 PM   #7
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I'm running a pinkish bulb along with an actinic now. I had a 6700k in there instead of the 03 but really wanted to slow the growth down some without reducing the light cycle to under 6 hours. I do blast the very back of the tank for 1.5 hrs/day with a 6700k to keep the rear stems from leaning forward so much. Guess I'm tired of the extra yardwork right now. lol
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Old 08-25-2011, 05:09 PM   #8
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Quote:
Originally Posted by sink View Post
.... I've never experienced this myself, but I've heard it on the internet so it must be true.
That's why I'm so sure the Washington Monument now leans to one side.
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Old 08-26-2011, 01:23 AM   #9
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I use 5,500k bulbs in my Current hood and the reflector is so good it's very bright, but in my Coralife fixture the reflector is so hidden by the bulbs 6,700k bulbs do give a yellow appearance, but it's the fixture in my case.
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Old 08-26-2011, 02:32 PM   #10
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I have used 10000K PC and the plants grew great and looked awesome.

I agree mixing bulb spectra is a good way to go to get the look you want.
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Old 08-26-2011, 09:03 PM   #11
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One of the nicest looking tanks I've ever had was a 55g with 4 T8 tubes.


One "Marine Glo" 460nm blue, one 2700K warm white, and two 6500K daylight bulbs. Gorgeous.
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