# Light Spectrum and Plant Growth



## OhioPlantedtankguy (Aug 7, 2008)

Maybe SW bulbs aint so bad for plant growth afterall?


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## APCRandall (Feb 2, 2007)

Yea it looks like the bulbs we use arent as good for photosynthesis. I want to try one of them gro lights from phillips, saw them at homedepot. I belive there of the violet/blue spectrum. I think that people might just use the 6500k bulbs to make it look like the sun.


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## hoppycalif (Apr 7, 2005)

The more I learn about lights and the spectra and color temperature of bulbs, the more I believe that you can chose the bulbs you want based on what looks best to you. I don't doubt that there are some differences in growth rate for different bulbs, but I doubt that the differences are very great. And, color temperature seems to be very little more than a marketing technique.


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## OhioPlantedtankguy (Aug 7, 2008)

hoppycalif said:


> The more I learn about lights and the spectra and color temperature of bulbs, the more I believe that you can chose the bulbs you want based on what looks best to you. I don't doubt that there are some differences in growth rate for different bulbs, but I doubt that the differences are very great. And, color temperature seems to be very little more than a marketing technique.


Well my bulbs are being given to me free from the charity in my sig so i will not be complaining no matter what they are, but at some point when im setting up a high tech tank, i want the "Best Bulbs i can get".


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## pb300 (Jun 5, 2008)

Has anyone every tried using the UV bulbs for reptiles? I bought one that my girlfriend uses for her turtle and it puts out a very blue light. Would the UV-B add anything to plant growth or would the water simply block it?

One company even makes them in T5 sizes now.


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## Newt (Apr 1, 2004)

Lighting outside the visible spectrum doesnt do much for plants. As a matter of fact, infra-red will actually slow down photosynthesis and too much will inhibit it.

Bulbs come with all different spectral outputs and the intensity of the spikes can vary widely. Look for bulbs that come with a spectral output graph/curve and secondly look for the ones that quantify the output (Y-axis) in a term such as watts/per lumen/nanometer or Watts/nanometer per 1000 lumens NOT just relative intensity. Relative intensity means they take the highest peak in the graph and call this 100%; everything else is relative to that (i.e. 1/2 the height would be 50% and so on).

OhioPlant, that graph is typical curve for a plant called anacharis. I havent gotten to the botton of why this particular plants action spectrum is typically used. Here is a few more gifs to digest:




























This bottom gif is from a University study (cant remember which one) that was featured in a Journal of Plant Physiology article on photosynthesis. It shows a steep drop off after 453nm for chlorophyll b and the same for chlorophyll a after 662nm. This is why 460nm actinic usually dont work well and also why the far red doesnt either.









The only bulb I have run across that is largely red light is the incandescent light bulb:









If you have T5HO lighting why not use the Giesmann 6000K Midday:









Or the AquaMedic Planta bulb:









Both are very popular.


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## OhioPlantedtankguy (Aug 7, 2008)

Newt said:


> Lighting outside the visible spectrum doesnt do much for plants. As a matter of fact, infra-red will actually slow down photosynthesis and too much will inhibit it.
> 
> Bulbs come with all different spectral outputs and the intensity of the spikes can vary widely. Look for bulbs that come with a spectral output graph/curve and secondly look for the ones that quantify the output (Y-axis) in a term such as watts/per lumen/nanometer or Watts/nanometer per 1000 lumens NOT just relative intensity. Relative intensity means they take the highest peak in the graph and call this 100%; everything else is relative to that (i.e. 1/2 the height would be 50% and so on).
> 
> ...


In a perfect world where I had all the money i needed i would, but to be honest i couldn't even afford the bulbs i am getting a charity is providing them to me free of charge along with a plant package.Giesmann name is well known to me they are one of the most recommended bulbs in the SW end of our hobby, well know for quality but it comes with a quality price tag.

Check out the link in my sig that is the charity that is helping me out, very very good people, non profit, and they run on donations. Its good to see a charity that realizes there is more to life than food and shelter and that the poor need hobby's just as much as the wealthy do, if not more. When i look a life through my eyes ill be honest it is pretty bleak, to say the least. My tanks,frustrating as they are sometimes are the bright spot in that bleakness, along with my kids and Girlfriend.


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