# 6700K & 10000K pc combo is it good for growing



## baka (Jan 4, 2006)

Hi,

As the title says, my current bulb has a 6700k and 10000k and I havent seen much growth. Is this a plant bulb or should I get a 6700k or 5500k only.

Thanks


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## bigstick120 (Mar 8, 2005)

That is a fine, mix, one of my favorites!


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## xcooperx (Jun 24, 2006)

thats also my light combo, plants grow really well

I have a question though, what about 10,000 K only? can they grow plants??


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## Burks (May 25, 2006)

xcooperx said:


> I have a question though, what about 10,000 K only? can they grow plants??


Yes they can. I'm using only a 10,000k 96w PC bulb over my 40g breeder and I'm getting decent growth. This is without ferts or CO2.

Although I would rather have a 10,000k/6700k combo. The 10,000k just washes a lot of color out.

Anyone got a spare 96w 6700k bulb? :heh:


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## goalcreas (Nov 20, 2006)

I have that bulb also, 65 watt PC. I got dexcent growth with it, but when I added the coralife T5 No fixture with more 6700k (or 6500k) and the 5000k, that is when the plants really took off. I think it is both the addition of more light (obviously) but the addition of the other color temp that did it as well.
That is on a 29 gallon so there is a total of 101 watts now, so 3wpg next to 2.25 for sure the wattage has something to do with it, but I might add that the tank is more pleasing to look at now and with the 5000k it is not "brighter"
with more light, it is actually toned down a little, but man does it grow plants well and pearls great.


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## gibmaker (Jan 3, 2007)

I have four 36" pc that are 10,000k over my 125 gal since day one, great growth!


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## trenac (Jul 16, 2004)

My plants grow great with a 10000k bulb. The only drawback that I've found is that it also promotes BBA growth.


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## Burks (May 25, 2006)

trenac said:


> The only drawback that I've found is that it also promotes BBA growth.


Interesting. My tanks is getting BBA pretty badly. None of my other tanks have had it except my 40g breeder (the only one with a 10,000K bulb).

Coincidence?


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## bristles (Mar 7, 2006)

I use a combo of 6500K & 10,000K (for color enhancement) and my plants grow well.


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## trenac (Jul 16, 2004)

Burks said:


> Interesting. My tanks is getting BBA pretty badly. None of my other tanks have had it except my 40g breeder (the only one with a 10,000K bulb).
> 
> Coincidence?


I really don't think so. I have always had a 10000k on my 20g high and always had problems with BBA. I never crossed my mind that the bulbs K rating would have something to do with it. Then I purchased a 10000k for my 20G long. After about a week this tank began growing BBA also. I'm convinced it is the bulb.


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## Jdinh04 (Oct 7, 2004)

I also have a 6,700k/10,000k combo running on my 50g breeder. I just have the 6,700k on for now but I may boost the lighting a little bit and have the 10,000k bulb on for 3-4 hours or so.


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## ruki (Jul 4, 2006)

This 6700K 10000K combo works pretty well with those Coralife T5 fixtures.


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## goalcreas (Nov 20, 2006)

Ruki, was that last post a question.
YES, it is AMAZING to use the combo of both fixtures and the dual temp PC
I love it and know others who do it and have completly fallen in live with it.
I also know guys that are removing all of their PC's and replacing them strictly with the Coralife T5 fixtures.
Now that is on smaller or more shallow tanks however, for big and or tall tanks, they might not be enough to penetrate to full depth, for this I still use T5, but I use HO in a Tek fix, but there I also mix up the color temps of the bulbs to get 10,000k and 6500k and 5000k(pink) I may or may not try one of the blue bulbs sometime to see if I like. The Tek is just sooooooooooooo bright with the aqsome reflection it gets, the blue bulb might tone it down a bit and might be beneficial to red plants (might not, somebody help me with this thought).


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## Newt (Apr 1, 2004)

Choosing lighting that is beneficial for plants based solely on the kelvin rating is really worthless. It is hit or miss to get a bulb that has the correct spectra that will promote good and healthy plant growth. You need to know the spectral output of the bulb. The kelvin rating is more or less a matter of taste as to how it makes your tank look.


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## ruki (Jul 4, 2006)

Newt said:


> Choosing lighting that is beneficial for plants based solely on the kelvin rating is really worthless. It is hit or miss to get a bulb that has the correct spectra that will promote good and healthy plant growth. You need to know the spectral output of the bulb. The kelvin rating is more or less a matter of taste as to how it makes your tank look.


It might be a bit better than that. 

For my post, I should have specified Coralife T5 bulbs. Those are the easiest to obtain, but I'm going to have to look around a bit for a non-green spike 6xxxK bulb...

There are many different bulb spectrums that can be marketed as the same Kelvins tube. Some of these will be better for plants and others worse.

However, one can generally conclude that a 10000K marketed tube has more blues than a 6500K tube and likewise that has more blues than a 4100K tube.

But, it is limited and too many people use the numer as some sort of absolute.

I think a great part the successs with mixing tubes is that the individual tubes were not optimal for growing plants and using two different marketed tubes makes if more likely to get more spectrum that plants will utilize.


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## ruki (Jul 4, 2006)

goalcreas said:


> Ruki, was that last post a question.
> YES, it is AMAZING to use the combo of both fixtures and the dual temp PC
> I love it and know others who do it and have completly fallen in live with it.
> I also know guys that are removing all of their PC's and replacing them strictly with the Coralife T5 fixtures.


I've been replacing my old T12, magnetic ballast fixtures with Coralife fixtures mainly to reduce my electricity bills. Once you have more than a dozen tanks, it starts to become a noticable monthyl difference. 
I wish Coralife used better reflectors in these fixtures though. I'm guessing that they are wasting at least 1/4 of the light with the lame reflector. But, even this lame reflector was better than the reflector in fixtures I replaced.



> Now that is on smaller or more shallow tanks however, for big and or tall tanks, they might not be enough to penetrate to full depth, for this I still use T5, but I use HO in a Tek fix, but there I also mix up the color temps of the bulbs to get 10,000k and 6500k and 5000k(pink) I may or may not try one of the blue bulbs sometime to see if I like. The Tek is just sooooooooooooo bright with the aqsome reflection it gets, the blue bulb might tone it down a bit and might be beneficial to red plants (might not, somebody help me with this thought).


That's a good question. Once you get away from the typical green plants, how do spectral needs differ for the fancy plants with non-green leaves?


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## Newt (Apr 1, 2004)

Well, ya. Ok, Ruki. Just about any light has useable energy for plants. Not a coralife fan at all, thou. Way too much green in the spectral output.


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