# blue light special....



## clay (Jul 3, 2004)

what are your takes on using either a 50/50 bulb or one white one blue on a planted tank? do you think the growth will be better or worse and why?

thanks....

clay


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## Jason Baliban (Feb 21, 2005)

The blue light does little for plants needs. It is not the correct spectrum for to be utilized for photosynthesis. You could try it, but I think you will have more luck with all white bulbs. Let us know if you try it.
jB


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## trenac (Jul 16, 2004)

The blue bulbs are used for marine tanks for coral growth, they have little affect on plant growth. You would better off using the white plant bulbs (5500k-10000k), this way you will get full benefit from the bulb.


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## Sir_BlackhOle (Jan 25, 2004)

I use a 55 watt half blue actinic half 10,000k. I kinda like the look of it. It doesnt appear to affect plant growth, but I dont have anything to accurately compare it to.


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## clay (Jul 3, 2004)

i do admit that i already have a two 50/50 compact bulbs on my 30g. there are 2 whites too. i have heard that blue lights tend to make the plants grow more compact. has anyone else heard this?


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## TWood (Dec 9, 2004)

trenac said:


> The blue bulbs are used for marine tanks for coral growth, they have little affect on plant growth. You would better off using the white plant bulbs (5500k-10000k), this way you will get full benefit from the bulb.


Not true.

From: http://www.marineland.com/reports/3Lighting.asp

"Plant tanks require the correct lighting to be successful. The number one reason for lack of success in growing plants in an aquarium has to be the use of the wrong lamp. Plants have two types of chlorophyll; a and b. Chlorophyll a absorbs light at 405 and 640 nm. Chlorophyll b has a peak absorption at 440 and 620 nm. Plant lamps are designed to emit light at the red wavelengths to duplicate the job of the sun. But too much red color can cause aquatic plants to grow tall and thin. For best results, use a daylight (5,000 °K) lamp such as an Aquasun, Ultralume 50 or Chroma 50 in combination with an actinic white or actinic day lamp. The actinic day or white lamp is a mixture of 50% actinic (blue light) and 50% daylight. In large or deep aquaria consider using HO or VHO lamps."

And:

"Wavelength is another terms that is important to understand especially in the context of lamp descriptions such as full spectrum or peak wavelength. These terms refer to the wavelength output of the lamp or bulb. Actinic lights, for example, produce only light at a specific wavelength - 420 nm. This peak wavelength value, which produces a very blue light, was chosen because during photosynthesis chlorophyll a absorbs light near this wavelength. To promote photosynthesis in reef coral actinic lamps are used. Some lamps have two, or even three, peak wavelengths."

Then look at the spectrum charts here:
http://www.championlighting.com/e/e...ing.html?link=/Products/Lighting/pclamps.html

Chlorophyll is chlorophyll, plants or corals, to some extent. I've seen tanks with 25% of the lamps as actinics and it's a nice look - dark and broody to the eye but still grows plants.

TW


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## clay (Jul 3, 2004)

i'll admit, i thought there was some affect to have the blue. to recap, i have 2 50/50s and 2 white. thanks for the article. very informative.


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## trenac (Jul 16, 2004)

TWood said:


> Not true.
> 
> TW


Which part?...Blue light being used for Marine tanks or white plant bulbs for plant growth.

I'm not saying you cannot use actinic blue for plants or actinic blue does not have any effect on plant growth. I'm saying that reef tanks benefit from Actinic blue bulbs more than planted tanks do.

Planted tanks benefit more from lower kelvin ratings (5500k-7500k/full spectrum lighting) and marine tanks benefit more from higher kelvin ratings (10000k-20000k/bluer lights).

Photosynthesis is most intense in the long-wave red and short-wave blue and blue and green light for metabolic processes in reefs.


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## TWood (Dec 9, 2004)

trenac said:


> Which part?....


This part:



trenac said:


> The blue bulbs are used for marine tanks for coral growth, they have little affect on plant growth.


Then you said:



trenac said:


> I'm not saying you cannot use actinic blue for plants or actinic blue does not have any effect on plant growth.


But that's the way the earlier statement reads to me.
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trenac said:


> I'm saying that reef tanks benefit from Actinic blue bulbs more than planted tanks do. Planted tanks benefit more from lower kelvin ratings (5500k-7500k/full spectrum lighting) and marine tanks benefit more from higher kelvin ratings (10000k-20000k/bluer lights).


Define "more". According to the linked article, plants can use both ends of the spectrum.
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Marineland Article said:


> Actinic lights, for example, produce only light at a specific wavelength - 420 nm. This peak wavelength value, which produces a very blue light, was chosen because during photosynthesis chlorophyll a absorbs light near this wavelength.


Unless plants have no A type chlorophyll, how could an actinic lamp -not- be beneficial? The Kelvin scale is more useful when choosing appearance to the human eye, IMO.

TW


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