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Has anyone done any experiments on the effect that different color temperatures have on plant growth?

Does 2700k not do as well as 10,000k, or is it really just a visual preference?
 

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warm light

One of my LFS is a really unusual place. There are over 100 planted tanks and the owner is both ingenious and frugal. When "energy saving bulbs" first came out he was one of the first to try screwing them into incandescent hoods or making DIY fixtures to grow plants. His tanks are very low tech, most are fairly low light and have no CO2 or have DIY yeast bottles. He does have algae along with the plants, but his fish loads are really high since he's selling out of them, and I don't think he mucks around with balancing ferts much, he mostly uses a little Kent freshwater plant. Hey, the guy has to maintain over 100 small tanks! His tanks are not Amano style, he has his own style.

I'm guessing the light is around 2700K, some are higher. He says the warm light looks like sunset and I agree. I'm fond of it and one of the things I'm not sure I like in my more expensive high tek setup is the white color of the 6500K lights. I have set up nano tanks in 5 1/2 gallon all glass tanks with a couple of 14 to 20 watt compact fluorescent bulbs and CO2 pressurized injection through a limewood airstone and the plants would pearl and grow. Leaves would be smaller but this really suited the nano tank. I think fish like the mellower light too, especially apistos and blackwater tetras.
 

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IMHO, 6500/6700K and lower looks like pee in the water. If possible, I try for a mix of 6700K and 10,000K or I go for the 8,800K bulbs.

But back to your original question, plant growth has almost nothing to do with color temperature. What matters is the spectrum of light that the bulb puts out. If it falls within the range of useable light for plants, then they'll grow, despite the color temperature of the bulb. If the bulb suits your eyes but puts out the wrong spectrum, your plants won't grow well.
 

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these are some of the best graphs I've seen - just go to the bulb manufacturer website and match the spectrum graph of the light to the action region in the second graph. Color temp really means nothing to the plants. You'll be concerned mostly about energy levels at specific wavelengths to get the best light absorption. Lower color temp lights will make white appear more and more yellow higher color temps will make the white point closer to blue.

-Rich
 

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both

But is that fish store growing plants or storing plants?
The store is unusual in that all the tanks are planted displays in which fish and plants are for sale. Some plants are there for years and others sell fast. It's especially nice because often one can buy a plant that has been kept long enough in local water to have acclimated, possibly grown roots, and, if applicable, changed from it's emersed to submersed form. Others just fly out the door however. Lots of people know what day he's getting plants! :icon_roll
 

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colormax bulb

Check out the top couple inches rotala growth in my several weeks old, no filter, no CO2 (4 drops Excel a day and a little K) 4 1/2 gallon tall betta bowl with a 20 watt colormax CF bulb.
I'm not sure what the relationship between nm in the charts above and degrees Kelvin is. I've read that plants like the red and blue light, but not the green, which is why they reflect it back. Warmer light has more red, cooler has more blue. "Grow" lights have the red and blue without the green, hence they look a dim purple to us but plants love them. I think the colormax is kind of like a grow light. I used to inject CO2 into this and plants pearled and grew really fast.
 

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do you mean mixing >7500k(blue colour) and <4000k (red colour) light bulb will give a best environment for growing plants ?

I heard people said getting a 6000-7000k light bulb best for aquarium plants.

Need help here,need to get a new aquarium light bulb for plants.
thanks :)
 

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since the blackbody temp of our sun is roughly 5,800K and considering plants have evolved for millions of years under these conditions, it's not surprising they do well with those color temps. like epicfish mentioned previously, i too like to mix it up with a white'r 10,000k bulb for aesthetic reasons.
-snafu
 
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