# 4000k



## rabidrider (Jul 18, 2014)

I have a 4200 in my sump growing pickerel weed and so far it works pretty good. I do have alge down there though but I also leave the light on 24/7 in the sump. As far as growth I have not noticed much difference. 

Have you tried home depot for a 6500. Thats really the only place I tend to find them. I settled this time as I moved and a home depot is quite a ways from me.


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## GraphicGr8s (Apr 4, 2011)

He's in Norway. I doubt there's a HD near him.

No wonder the reds pop. The 4200 has more red in it so it enhances it. Personally I like the 65-6700K bulbs and seem to get better growth. The plant and aquarium bulbs are way too red for me and are in the 2-3000K range

You leave the lights on 24/7? You do realize plants need a dark period don't you?



> First, in the photosynthesis process itself, there is a reaction known as 'dark reaction' pathway or lately known as 'carbon reaction' pathway where the free energy of ATP and reducing power of NADPH, are used to fix and reduce CO2 to form carbohydrate. This is very important process to release Oxygen into the air. This happened in the dark or at night.
> 
> Secondly, for inducing the plant to initiate flowering process. This phenomena is known as photoperiod, ie based on the ratio of the daylength to night length over 24 hours. Plants reaction to photoperiod can be divided into 4 groups.
> 
> ...


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## Raymond S. (Dec 29, 2012)

In these matters only putting it on the tank for a while will decide that.
"K" rating is an industrial rating, not a plant/horticulture rating.
6500/6700K are what commonly works best on plants but there ar exceptions as spectrum is the key here.
General Electric is a company that is usually just called GE. I wrote it out for you
because of where you are and my thinking it may not be common there.
They make a "Plant & AQuarium" bulb that enhansed red and blue spectrums in
it but is only 3100K and it grows well. Has a fairly dim amount of visible light though
when you compare it to say a 6700K bulb.
Just try the bulb for 90 days to see how it works.


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## rabidrider (Jul 18, 2014)

GraphicGr8s said:


> He's in Norway. I doubt there's a HD near him.
> 
> No wonder the reds pop. The 4200 has more red in it so it enhances it. Personally I like the 65-6700K bulbs and seem to get better growth. The plant and aquarium bulbs are way too red for me and are in the 2-3000K range
> 
> You leave the lights on 24/7? You do realize plants need a dark period don't you?



Thats just on my sump that runs 24/7. I am new to fresh water tanks and am running under the same basic principles I ran my reef tank. The refugium on my reef grew macro alge like crazy running 24/7. Now I could be wrong by doing it on my fresh water. Tank is still pretty new (as far as the plants are concerned). Not sure what the difference would be as far as fresh and salt water is concerned (still got a lot of learning to do). In my reef the only real reason you shut off lights was to hold down on alge growth (and helped to promte spawning on coral somewhat). In the refugium I always left it on and grew all kinds of alge. Never had an issue in the display tank with any alge. What I do not know is if it actually had anything to do with the refugium or the fact I keep water changes religiously in check.

The way I figure it though this is why I joined this forum. To gather information from more knowledgeable people in the planted tank world. Then through a lot of patience, trial and error I will find what works for me. I did start a thread of my tank (dont mean to hyjack this one) waiting for the mods to approve it in the tank journal section. However any info of pros and cons on lighting cycles is always helpful on any thread.


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## GraphicGr8s (Apr 4, 2011)

RRider, that's why I try to post with something to back up my opinion. BTW I find when Newbies start asking questions it gets those in the hobby to actually think about why we do things. At least it does for me. Like a "refresher on basics". 

Jnad, that's more a "warm white". How available are LEDs? Or can you order online?


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## Jnad (Aug 17, 2012)

Hello!

I have tried to take some pictures of the same tank with 3 different bulbs, but the pictures does not show the right colors. The 4000K bulb make the red pop mutch more, it does not show on the pictures. The most dull color is the 6500K flood led.

I do actually like the 4000K bulb, it makes very nice contrast between red and green.

Not comparebale pictures, but i post them any way, the water is somwhat cloudy, it is very hot here in Norway now, and the tank seems to suffer.

Picture 1.
18W PL 6500K

Picture 2.
10W Flood Led 6500K

Picture 3.
15W CFL 4000K


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## GraphicGr8s (Apr 4, 2011)

Jnad, the 4000 makes the reds pop because there is more red in the light. 
I use the 6500 not for how it looks to me but it seems like my plants do better with it.


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## Raymond S. (Dec 29, 2012)

I can see clear differences in each bulb in those pictures and I like the bottom one best
as it has less dark spots towards the back.


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## Wasserpest (Jun 12, 2003)

Keep in mind when discussing color temperatures that a single number like 4000 or 6500 can't describe a spectrum. Yes, generally lower numbers equal more yellow/red, higher numbers more blue, but in reality that number means very little. Especially when you get into plant grow bulbs with peaks in the red and blue spectra it gets totally quirky.

Second point I'd like to make is that this number also means not much to plants. Saying that a 6500K bulb grows plants better than a 4000K bulbs is wrong IMO. If most of that 6500K peaks in the green spectrum, it's PAR will be fairly low. And even so, as long as there is a minimum threshold in light reaching the plants, they may not care and/or adjust to different conditions.

Just be aware when throwing around numbers. Two bulbs with the same K color temperature can look totally different.

And one last point... when you take pictures of your tank, your cameras auto white balance will always balance the tone in some way, so what you see with your eyes is not what you get with your camera. If your camera permits, you CAN set the white balance to a specific value, say 5000K, or something like "Fluorescent", and then it will let you make some comparisons.


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## jeffkrol (Jun 5, 2013)

Wasserpest said:


> Keep in mind when discussing color temperatures that a single number like 4000 or 6500 can't describe a spectrum. Yes, generally lower numbers equal more yellow/red, higher numbers more blue, but in reality that number means very little. Especially when you get into plant grow bulbs with peaks in the red and blue spectra it gets totally quirky.
> 
> Second point I'd like to make is that this number also means not much to plants. Saying that a 6500K bulb grows plants better than a 4000K bulbs is wrong IMO. If most of that 6500K peaks in the green spectrum, it's PAR will be fairly low. And even so, as long as there is a minimum threshold in light reaching the plants, they may not care and/or adjust to different conditions.
> 
> ...


I pretty much second all that..
But w/ "normal" LED's it is relatively simple. 
On a side note a LED 6500K is a range.. say 5500-7000... depending on manuf. tolerances..
Flour ect.. not so simple.. spetral peaks and proportions can be all over the board and still give 6500K CCT.. (correlated color temp. is an average of all wavelengths)


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## gus6464 (Dec 19, 2011)

You also have to start taking into account CRI as it's what the industry is using to describe the spectrum of a bulb. For example a 5000K 70CRI and 90CRI while the same color temp will have a different spectrum. The higher the CRI the more red it will push.

Here is an example between 3000K LEDs:





































All are same color temp but spectrum is quite different.

And multiple CFL bulbs with a temp of 5500-5600K.




























As you can see all the same temp but spectrums not so much.


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## jeffkrol (Jun 5, 2013)

CRI is problematic;









Re: to metal halide.. LED is worse.. 


> A palate consisting of eight (8) colors (R1 through R8) is used as the “standard” to calculate CRI. This rating system is designed specifically for visual display lighting and really has little correlation to true sunlight spectrum (as defined by ASTM/IEC/JIS. In fact, some lamps may have a CRI of 100 but still not even qualify for Class C solar spectrum matching. One major problem is that even colors such as R9 (red), one of the most common processed colors, is not one of the 8 colors used in calculating CRI as this color is difficult to achieve with standard metal halide technology.


http://www.eyesolarlux.com/light-technology/light-faqs/


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## GraphicGr8s (Apr 4, 2011)

Kolor temp is akin to paper brightness. There are a multitude of papers with a "100" brightness yet they are not white. Well some are.

It all depends on how the paper was bleached. If they use titanium oxide the paper will be a bright white. It is an expensive paper. If you want the same brightness you can get it much cheaper. But the paper will be a shade of blue. Both are 100 bright but both are not white.


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## gus6464 (Dec 19, 2011)

jeffkrol said:


> CRI is problematic;
> 
> 
> 
> ...


I am not arguing on the measurement of CRI. I am just pointing out what the industry is using to give an idea of spectrum. The common denominator is that the higher the CRI the manufacturer advertises, the higher the red push in the spectrum. One can argue about this all day long but it's what the industry tends to be using. Also in the cool white range it will push out a lot more cyan/green.


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## jeffkrol (Jun 5, 2013)

gus6464 said:


> The common denominator is that the higher the CRI the manufacturer advertises, the higher the red push in the spectrum.


I just pointed out that was incorrect.. look at the main 8 swatches..
They are pastels..

http://cool.conservation-us.org/byorg/us-doe/color_rendering_index.pdf



> Now look at the SPD for an RGB LED in Figure 2 above. It’s similar to the fluorescent
> lamp in its “spikiness,” with obvious blue, green, and red peaks. It scores only 27 on the
> CRI metric because those particular wavelengths don’t perform like incandescents on the
> eight sample CRI colors. Regardless of low CRI, the white light generated by commercial
> ...


figure 2 is high in red.. w/ a CRI of 27.. 

Addendum:









"normal" LED









We both have some "rightness".. 


you can get a lot more red in low CRI LED's, and high CRI's just don't push more red.. it is a combination of "flattening" the spectrum across the board..

AND you have to know exactly how they test CRI. If using the "standard" 8 patches..or the full set..



















> CRI is the average score of 8 color samples


http://store.yujiintl.com/pages/frontpage


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## Jnad (Aug 17, 2012)

Thanks for showing interest and posting in this thread.

I dont have any comments, but i really like how the 4000K bulb is coloring the tank. In real time there is a huge difference in those 3 different bulbs, not like in the pictures.

I like the look of the 4000K and i will try it out for some time. 

If i can get my hands on a camera that take better "real time" colored pictures i will post them.

Jnad


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## gus6464 (Dec 19, 2011)

Second pic shows almost no output in the 660 region so makes sense why it's 27CRI. The high CRI pic has at least double the output in that region.


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## micheljq (Oct 24, 2012)

Even 4100K look can vary from one manufacturer to other. Philips 4100K fluorescents I had for kitchen looked very daylight, while some 5000K CFLs from another manufacturer I had had a "yellowish" look.

On another matter when I was young, one friend did successfully grow Java Moss in a 10 gallons tank, with an ugly yellowish incandescent bulb, it must have been 2700K. Java Moss did fill the tank.

Michel.


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## jeffkrol (Jun 5, 2013)

micheljq said:


> Even 4100K look can vary from one manufacturer to other. Philips 4100K fluorescents I had for kitchen looked very daylight, while some 5000K CFLs from another manufacturer I had had a "yellowish" look.
> 
> On another matter when I was young, one friend did successfully grow Java Moss in a 10 gallons tank, with an ugly yellowish incandescent bulb, it must have been 2700K. Java Moss did fill the tank.
> 
> Michel.


Incandescents are good plant bulbs. It is the heat and inefficiency that is the problem.. Very rich in red which is why they look so "yellow".. 
third problem.. looks.. 









ADDENDUM re: CRI



> Increasing color saturation
> This fact suggests that we may prefer lighting that increases color saturation. By enhancing the amount of light at key wavelengths in the sources’ SPDs, we could increase the color saturation or chroma of specific colors and in the process reduce the CRI. With LEDs, this is easy to imagine. If we wanted to enhance the primary colors we could mix in additional red, green and blue light from red, green and blue LEDs along with a typical white LED (Fig. 7).
> Fig. 7. Adding a red LED (640 nm), a green LED (525 nm) and a blue LED (460 nm) to the white LED shown in Fig. 6 results in a 5500K light with a CRI of 81. Reds and greens and purples will appear more saturated under this light than under the light in Fig 6.
> Fig. 7.
> ...


Bump: Swatch spectrum for fun.. R9 starts high @ about 625


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## Jnad (Aug 17, 2012)

Hello!

Restarted a tank and put in a 4000K bulb, it shure looks nice.

I think i will start using 4000K bulbs instead of 6500K, i like the looks of how it color the green and red plants, hope it will grow plants also

Jmad


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