# 10,000 kelvin bulb for good sidegrowth?



## Hanzo

Below are a small part of an articel focusing on light on terrestial plants. There's much I don't get in this, since english is not my first language, but from what I understand i says that at a certain kelvin rate, the light seems like the light that can be found underneat a canopy of leaves, and this light will make the plant struggle to grow upwards towards the canopy to get to the light itself. On the other hand, and a nother specter of light, it works like direct sunlight, so the plant focus on good sidegrowth.

here's the articel in full:

http://194.236.255.117/akvarienet/memberfiles/th_of_plantsfile54.pdf

And the part we are looking for:
5.3 Stem elongation
As described in section 2.2, far-red light reflected by neighbouring plants (or neighbours for short) decreases R:FR in horizontally propagated light, as 'seen' by vertically oriented plant surfaces (see Aphalo and Ballaré, 1995). This happens at low canopy densities, so it is especially important for small seedlings in sparse canopies.
The stems of many plants elongate faster if they receive additional far-red light from the side (see Ballaré, 1999, and references therein). In general, the magnitude of the response to far-red
light depends on the species, developmental stage, and other environmental variables such as blue light and/or photosynthetically active irradiance incident on the leaves. However, at low canopy densities there is no actual shading of leaves by neighbours. When measured under laboratory conditions, the stem elongation response to far-red light incident on the stem can be shown to have a very short lag (of the order of minutes in small seedlings) but continue for some time after the end of the stimulus (Casal and Smith, 1988a,b).
The photoperception of the lateral far-red light takes place in the growing internodes. In sparse canopies, the perception of neighbours is mediated mainly by phyB and probably sensitivity is modulated by phyA6.

Intensiteten och den blåa delen av spektrat verkar inte ha någon betydelse om man kollar på den bild han visar (Figure 11) där han jämför HighLight (HL) och (LowLight) och antingen Far-red eller Red.

This has been dicused on a swedish forum the last few days, and many of the skilled plantedud's there seems to swear to 10,000 kelvin bulbs for good growth and strong red collors. I have always been under the expercion that around 5500kelvin was the only way to go. Anybody here had any experience with bulbs in this range for a freshwater planted tank?

Also, I'm wondering if I should try this over my tank. What would be the best combination, two 10,000 kelvin 150W MH, or 4 70W, two at 5000 kelvin and two at 10,000 kelvin?

Kind regards,
Hanzo


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## Justin Fournier

I have always been curious as to why more people didn't use the 10k's in FW, as they have a far nicer CRI then the commonly used 6700's or 9325's. I use both the 6700's and the 9325's together and find the results more then satisfactory. If I could only use one K though it would be 10ks. I think you could grow plants under any reasonable spectrum really.

Perhaps now is a good time to switch the 6700's out in favour of some 10's. I will consider it if I have a few extra bucks to blow.


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## IUnknown

I have started to use a combination of 10,000K and 6500K. The internode length of the plants is more compact and my Micranthemum has started to creep. But it might be because the intensity of the bulb is higher because it is new. Although I have left one of the two 6500K 13 watt bulbs off.


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## missphnx

Don't the 10,000k has a very blue light? I don't know.
I am trying to figure what bulbs to use myself. These 9325k's that everyone is talkign about. Where do you get them? Do they make them for a PC retrofit? I am getting a 2x44w PC retrofit kit from Ah Supply and I can't decide what Kelvin to use in it.


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## IUnknown

All glass uses them in there compact flouresant strip lights. There are cheaper places to get the but,
http://www.drsfostersmith.com/product/prod_display.cfm?pcatid=3773&Ne=40000&R=6497&N=2004+113030


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## bharada

I just redid the lighting on my 40gal with two 96W PC strips. Right now both have 10K bulbs which are very white...which would look awesome over a reef tank, but it doesn't flatter any of my red plants. I have some 8800K bulbs coming in on Friday so I'll try switching them up...try 10K/8800K or 2 8800K and see what looks best.

My old lighting was a combo of one 50/50 PC (ordered the marine Aqualight by mistake) paired with three NO 30W tubes (2 6700K + 1 18000K Power-Glo). Having the Power-Glo's purplish tint really did a lot to enhance the look of the red plants. Too bad there isn't as much variety in PC bulbs.


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## IUnknown

I've read that 6500K is for growth and 10000K is for color. I switched to 10000K and had to change my dosing because things slowed down. I've been using a combination of 6,500K and 10,000K recently and things are great. Hanzo, I would do a combination just for the look, not to yellow not to white, but just perfect. If its a big setup and you are using four fixtures I don't know how you would mix the light. A lot of fixtures come with PC's to supplement the color. You use 6,500K MH bulbs and then 2 x 28 watt 10,000K bulbs to balance the color. Justin, I would stick with what you have, I think that is the ideal mixture. I just ordered a 6,500K MH with a 55 watt 9325 GE bulb to balance the color for a 20 gallon.


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## gpodio

The last photo in this article is of a fixture containing two Coralife bulbs,a 10000K and 67000K, you can easily see the difference using a camera. To the eye it's very difficult to see the blue. I like this combination personally even though I haven't used it in a while now, but had no problems growing plants with it that's for sure.

Consider however that not all 10000K bulbs look the same, some have more dominant peaks in their spectrum that give them a different appearance.

http://www.gpodio.com/overdrive_twin_strip.asp

Giancarlo Podio


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## freshreef

sorry to interupt but i never used other bulbs eccept 6500k, 4000k 3000k and sylvania gro lux . at the mom im having 6*39w t5 (3*6500, 2*3000 and one 4000k) do u realy think i should try one of those 10000k t5's? 
whats the benefit of the 10000k in the planted tank? i always thought its for s/w only...


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## lemonblazer

I have a similiar question so I'll post here. I'm about to get a light with 6 x 65w bulbs. I'm wondering if using all 6500K bulbs will wash out the colors of my fish. Will using 6 10,000k daylight bulbs have the same affect? I want good plant growth but I don't want my tank to look washed out. Does it make sense to mix bulbs when they are both white?


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## david lim

Hanzo said:


> Below are a small part of an articel focusing on light on terrestial plants. There's much I don't get in this, since english is not my first language, but from what I understand i says that at a certain kelvin rate, the light seems like the light that can be found underneat a canopy of leaves, and this light will make the plant struggle to grow upwards towards the canopy to get to the light itself. On the other hand, and a nother specter of light, it works like direct sunlight, so the plant focus on good sidegrowth.
> 
> 5.3 Stem elongation
> As described in section 2.2, far-red light reflected by neighbouring plants (or neighbours for short) decreases R:FR in horizontally propagated light, as 'seen' by vertically oriented plant surfaces (see Aphalo and Ballaré, 1995). This happens at low canopy densities, so it is especially important for small seedlings in sparse canopies.
> The stems of many plants elongate faster if they receive additional far-red light from the side (see Ballaré, 1999, and references therein). In general, the magnitude of the response to far-red
> light depends on the species, developmental stage, and other environmental variables such as blue light and/or photosynthetically active irradiance incident on the leaves. However, at low canopy densities there is no actual shading of leaves by neighbours. When measured under laboratory conditions, the stem elongation response to far-red light incident on the stem can be shown to have a very short lag (of the order of minutes in small seedlings) but continue for some time after the end of the stimulus (Casal and Smith, 1988a,b).
> The photoperception of the lateral far-red light takes place in the growing internodes. In sparse canopies, the perception of neighbours is mediated mainly by phyB and probably sensitivity is modulated by phyA6.


Hey hanzo,
I just finished a plant physiology course that discussed this same topic. What you are writing is just about right. Keep in mind these tests were run on terrestrial plants and not aquatic plants. I do not believe a paper has been published concerning this with aquatic plants. Again, what you are writing is right. Red light plays a very important part in plant development as plants use the light during photosynthesis and make sugars. Well, underneath a canopy, light that filters through the leaves is mostly far-red light and not the red light that the plants need. To compensate and gain red light plants have a special hormone phytochrome (phyB and phyA6) which tell the plant to morphologically change its growth pattern to reach above the canopy and reach the red light which is more beneficial in photosynthesis. So phytochrome is very important in telling plants when it is underneath a canopy and not receiving the right type of light or directly in full sunlight.

When a plant reaches red light and blue light then morphology again changes from far-red light. Blue light causes the plants to become more compact whereas the red light causes the plants to produce more leaves. In full sunlight, blue and red light are dominant. Red and blue light tell a plant to stop growing tall and instead become more compact and horizontal. Again, phytochrome and another hormone, cryptochrome, tell a plant to do this. Hope this helps to clear anything up.


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## Hanzo

Indeed it did, many thanks!

Now, if I could only get some MH bulbs that would fit the bill. There's plenty of 10,000 kelvin bulbs out there rich in blue light, but missing in red. Pluss, nobody care to give me a color charts of the bulbs so finding the right on is really looking for the famous needle in the haystack :roll:


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## gpodio

Hanzo, there are many MH bulbs that will fit the bill, personally I think most 10K and lower will work for the plants, the rest is mostly for your eyes. Most of the people I know using MH/HQI bulbs are running 10K and particular interest is shown towards the OSRAM POWERSTAR HQI-TS 150W/NDL (never checked for availability in the US). But look around because you can get various kelvin bulbs from the many online retailers that cater for reef folks.

Here's a little homework for you :wink:

http://www.cnidarianreef.com/lamps.cfm

http://www.advancedaquarist.com/issues/oct2002/feature.htm

http://www.advancedaquarist.com/issues/nov2002/feature2.htm

http://www.advancedaquarist.com/issues/may2004/review.htm

http://www.advancedaquarist.com/issues/feb2002/Feature.htm

Hope that helps
Giancarlo Podio


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## defdac

Hanzo said:


> but from what I understand i says that at a certain kelvin rate,


Not the Kelvin, but the Far-red-ratios. Kelvin-numbers doesn't tell you how the spectrum looks like. More kelvin more blue, sometimes, but not always.

I guess you could make both a high- and low-kelvin bulb with high output in the far-red-areas.


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## OakRaid

I am running a 2 x 65 PC, 6700 (also one four foot 40 watt)
My plants sem to get rather long stems, between leafs.
Would changing the 6700's to 10k's help compact the growth, or am I reading at this wrong??


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## OakRaid

I am running a 2 x 65 PC, 6700 (also one four foot 40 watt)
My plants sem to get rather long stems, between leafs.
Would changing the 6700's to 10k's help compact the growth, or am I reading at this wrong??


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## defdac

OakRaid said:


> Would changing the 6700's to 10k's help compact the growth, or am I reading at this wrong??


Not necessarily. It's not the Kelvin as I said, but the relationship between the far-red and red-ratios.

The 10K bulbs that really smacks down the plants I've tried is Philips Aquarelle, Sylvania Aquastar and Triton (all 10 K)

The bulbs that get the plants to really elongate with long inter-node spaces is for example GroLux (about 4 K?) and Halogen.


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## OakRaid

the 2 x 65 PC lights I am using are 6700's from Hellolights .. Would you know if these bulbs would have a long stem affect on the plants?
The 4ft 40 watt fixture just has a sylvania daylight bulb in it.
I am using that because with the narrow beam of the PC fixture, the 40 fills in the shadows up front.
I had thought about just adding another 2 x 65 PC fixture ... but thought maybe that would be to much light on my 50 gal. ( 48 x 12 x 18 )


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## ShaneSmith

I've got a related question. If say you have 6wpg of 6500 k, and 2wpg of 10k. Wouldn;t the plant be getting similar levels if not more blue with the 6500k set up?


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## defdac

ShaneSmith said:


> Wouldn;t the plant be getting similar levels if not more blue with the 6500k set up?


Yes but as I said it's not about the *blue* part. It's a relationshop between the far-red and red-ratios.


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## david lim

defdac, 
In class, I learned that the blue light does play a crucial role in changing the growth patterns of terrestrial plants. Is this different for aquatic plants? The red:far-red ratio is also important. Essentially you'd want a high red to low far-red ratio. But blue light and red light both exist in full sunlight and both play a role in the morphology of the plant. Maybe they have an additive or synergistic effect? But both go through the same pathway to get that compact/ bushy growth.


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## defdac

david lim said:


> Maybe they have an additive or synergistic effect? But both go through the same pathway to get that compact/ bushy growth.


That is very possible.

I was mostly refering to the article shown by Hanzo, and it speaks very little of blue light when it comes to growth-patterns.


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## gpodio

I think we should be starting to talk spectrum rather than kelvin. Unfortunately 10K does not necessarily mean that there is a strong peak in blue, it can also mean there is little red. Just compare the spectrums of different 10K bulbs to get an idea of just how little kelvin means to plants. Even to your eyes, some 10K bulbs look yellowish, others blue, others pure white... The AquaRays are another example, I don't know how they measured such a high kelvin on these bulbs but they are certainly redder than any 6700K bulbs to my eyes.

Here's some links that may be of interest in this topic:

http://www.aqua-web.org/users/saurama/index.htm

http://www.cnidarianreef.com/lamps.cfm

http://www.geocities.com/Heartland/Hills/2637/spectra.html

http://www.sylvania.com/forum/pdfs/faq0040-0800.pdf

http://ukrop.info/index.htm?file=http://www.msaqua.com/html/aqua/lamps/spectra/spectra1.htm

http://ukrop.info/index.htm?file=http://www.msaqua.com/html/aqua/lamps/spectra/spectra2.htm

http://aqua.passion.online.fr/pages/douce/articles/eclairage.html

http://www.thekrib.com/Plants/Tech/light-spectrum.html

http://www.naturacquario.net/lux/fluorescenti.htm

Happy browsing!
Giancarlo Podio


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## dennis

Time to resurect this thread folks I just go the new(my first) edition of Natural History 9/04 an dht elead article is "How plants see" co-authored by Yanovsky and Casal, the fellow from Hanzo's original post article.

Basically the say many of the same things that Hanzo stated and David Lim backed up from his recent learnings. One thing that David commented on


> Essentially you'd want a high red to low far-red ratio.


 seems to me to be the clue to this puzzle. In their experiment that Casal and others participated in was to subject plants, terristrial grass plant in the Argentine Pampas, to more red light at the base of their stems. While the extra red was not enought ot affect photosynthesis they still were fooled into thinking they were not ina crowded setting. Their findings support the fact that plants can detect and infer information based on ratios of different light spectrum. In this case Red to far-red.

Plants absorb light in the red an dblue spectrum, mainly, but reflect that in the green and far red spectrums. As plants become crowded in nature, the amount of far red light that is reflected off neibghoring leaves onto the bases of the plant is increased, telling that plant to produce more lateral growth and fewer tillers. For our puroses, this creates "leggier" growth. In our aquariums then, the best way to create more compact growth, with more side shoots is to provide that plants with lots of red but little far red light.

As David also stated, photo receptors are used by the plants to sense these ratios and control growth accoringly. I direct quote form Casal/Yanovsky's recent article best describes this. "In enviroments that sustain only a few plants the proportion of red light is high. That pushes the equiblrium toward the active form of phytochrome..suppressing the elongation of the stem. The plant starts to grow compact and robust." Phytocrcome is one of the photoreceptors. It has 2 forms, one absorbes red light and the other absorbes far red light. Then one absorbs more light than the other, the plants growth is signaled and change their growth patterns accordingly.

My question is, does anybody know of a list of the spectrums of various floresecent lights? I have seen one somewhere but can't find it right now. Intensity inthe aquarium is also important but obvoiusly the two relate.. I use Ge 9325 and find that they produce more compact growth and more side shoots. I would assume that a 20 watts florescent tube is reasonabley the sdame as far as intensity goes so I believe that the red spectrum of the varoius florescent fixtures are the main cause of diffenent typesof plant growth.

What do you all think of this?


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## defdac

I totally agree. I've read this paper, and it gives a bit more complex view than yours, but I think you have got it all right:
http://www.cc.jyu.fi/~aphalo/old_pages/pdf/notes1.pdf

Pages with different spectra:
http://www.iespana.es/aquagarden/fluorescentes.htm

On a side not I have made a Java-program which calculates PUR-efficiency for a spectrum+lumens+watts. Exactly by Ivo Buskos step-by-step-manual here:
http://www.aquabotanic.com/lightcompare.htm

So I've begun to extend his list quite a bit. My program digitize the spectrums automatically and I seem to get higher max-lumens than he does, but all in all I get pretty much the same figures.
I've collected my PUR-efficiency-calculations here:
http://194.236.255.117/defblog/permalink/1402.html

My blog now has RSS 2.0 syndication, so you can "subscribe" to it if you're interested in updates of this list:
http://194.236.255.117/defblog/rssFeed.xml


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## Daemonfly

Hrm... I do have quite a few 10k bulbs sitting around, and the 4x20w ODNO experiment didnt give the results I hoped  Think I'll move the 55w 9325k back over to the 29g and was gonna add a 2nd 55w, mgiht as well give the 10k a shot (not sure of the bulbs' actual spectrum though).


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## plantbrain

I think the ratio of R/FR is important here.

Triton's are 7200K color temps FYI.

The amount of Intensity at each peak over the entire specturum would be more helpful as far as the discussion, I do not think you will find any plant biomass growth differences between these bulb types.

As far as red color, I have discussed this extensitively in the past and we have shown quite clearly specifically in submersed aquatic red colored plants such as Eustralis, Rotala, Ludwigias that red color is neither a function of spectrum nor intensity but rather good nutrient levels and low (but stable) NO3.

I would certainly not go out and buy all sorts of colored bulbs for getting redder color. I did at one point for other reasons, but found no differences in the red coloration.


Regards, 
Tom Barr


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## Floro

Hello !!!

I was also wondering te effect of 10 k color will have on plants...

In Chile (my country) we use Philips TLD 840 (4000 K) and TLD 965 (6500 K) and we have excelent results in many ways. 

About inter node space, I would say that intensity plays an important role. For a 420 lt tank (110 gal) I use 3 840 and 2 965, that´s about 0.45 w/l or 1.6 w/gal and I get a relatively small inter node space. I´m also getting a nice red colour in many species (didiplis diandra for example).

Spectrum. The Philips 965 is a full spectrum fluorescent (they are not specially designed for aquarium) and I think I´m getting most of the red and blue for my plants there, althoug the 840 also emit in those areas but far more less. 

Colour temperature (° k). As I know, the °k of a bulb should help in getting a smaller inter node space. If you put two aquarium with the same plants and everything, and you use two bulbs that emmit in the same wavelenght but with diferent °k, I understand that you should get a smaller inter node space in the higher °k bulb tank.

As I have read here, I agree that a combination of all the factros is important. The right spectrum and the right intensity. You can play a bit more with the °k, but I will recomend a combination too. Remember that a higer °k would probably look better and it will be better for algae. (you will obtain less algae with higer °k).

Regards


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## Mortadelo

Very interesting thread. I have a couple questions?, what wavelenghts are considered far-red?, and, is there a way we could filter them leaving blue and red light alone?.


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## Mortadelo

Red peak wavelength 660 nm

far-red peak wavelength 730 nm

Thank you Mortadelo!.

Don´t mention it :lol:


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## plantbrain

As long as the CRI is nice for my eyes, I find little differences in the "bushiness" in SAM's(submersed aquatic macrophytes).

I can get very long internodal lengths with high K, lots of blue etc, as well as reds. I had some filters that allowed only 700, 650, 550, 450nm of lower energy wavelengths through.

I used them a couple of times.
But I'm not too interested in it these days.
Maybe in a couple of years.

Over the years I've found little evidence for SAM's and this whole blue light prevents algae and pentrates the water better etc or causes bushiness.

Sounds good and you can put it out there for support, doesn't mean a hill of beans in practical terms. They have the same relative growth rates(Cool whites vs any pricy plant bulbs) so if you have enough and do well with nutrients/CO2, then you can tell a lot more about the light itself and not some other confounding factor.

References are good if they are applicable.
The entire K+ blocks Ca++ mess was a classic case of that not being done, as are other ref's sometimes used to support certain arguements.
DW's book does this a number of times. If you apply her arguements off pg 107, the graph suggest NO3, not NH4 is preferred in planted aquariums. The graph shows NH4 uptake rate at zero under normal plant tank conditions while the NO3 rate is rather high. Add CO2 and this situation is even more pronounced.
Few plant tanks have 2.0ppm-to 0.5ppm of NH4 

David, are they still using the Taiz Zeglear text?
It's fairly good. 

Overall, I think folks have had a change in their preferences more than that these bulbs are truely better. Folks seem to have gone towards bluer/higher color temps.

Often intensity is a much larger player here.
As are the other factors, CO2/nutrients.

Unless you have a light meter, a lot of this is tough to tease apart. Few hobbyist own Li Cor stuff Few researchers do light responses with aquatics, George Bowes and a few students of his are the main group at UF in the USA, there might be a few others.

Regards, 
Tom Barr


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## Troy McClure

raising the dead...

Has any more information become available on this topic? Can we update it to include the spectra of T5HO bulbs?


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