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Discussion Starter · #1 ·
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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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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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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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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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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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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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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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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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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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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Discussion Starter · #12 ·
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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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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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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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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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 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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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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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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