Zarnon
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Lights (part 2) -Spectrum and HID
If you understand what the visible spectrum of light is (400-700) nm, then you will have an easy time following along. See previous post with links to basic concepts.
Plants use light as a part of photosynthesis, regulating rhythms etc. However, 'all light is not created equal'. Certain parts are more important than others. This includes the blue (400-500nm) and reds (650-680nm). This is where PAR gets off-base as it gives equal weight to this entire range (see previous post).
So what we're talking about is a 'plant sensitivity curve', right? A correct one would show higher levels of response to these two areas? Pic three and the link below are examples of them. There are also many wrong ones. Unfortunately these seem to appear a lot in hydro lit or MJ forums as well. The white line in pic 1 is an incorrect one.
(Another correct plant sensitivity curve from Univ. of Hamburg); http://www.biologie.uni-hamburg.de/b-online/e24/3.htm Note, two bumps at the distal ends of the spectrum (blues and reds).
Curve's differ, here's one for algae http://www.emc.maricopa.edu/faculty/farabee/BIOBK/pigment.gif
So is there a way to tell how my particular light breaks down? Color temperature is a good start.
'Color Temperature' is measured in degrees/Kelvin; The lower end is warmer (more reds) while higher is cooler (more blues). A HPS is 2000-3000k (3000 extended spectrum), while your MH can go from 3000-6500 (3000 also ex. spec). I've been able to find a color temp for all HID lights I've looked at.
Here are some examples of color temperature:
Sunrise/Sunset: 3200k
Halogen bulb: 3500k
Midday (sun overhead): 5500k
Overcast: 6500k
Shade 8000k
Blue Sky: 9000-12000k
We push 2000-3000 spectrum bulbs for flowering. Why is that? In the literature, a MH bulb is recommended if you have no access to sunlight while HPS are reccommended as a secondary + sun. Maybe it's b/c a nonextended spec HPS is creating a predominant red light, redder than a sunset and then intensifying it by a factor of ten.
I think of Kal-el on his balcony, checking out the Red Giant dominating the sky. Well, worked for Superman, surely Superbud?
Compare the spectral analysis for both. Pic 1 is HPS, 2 is MH. Compare both of them to an accurate plant sensitivity curve (pic 3).
Look at where they're going! Even the reds useful to the plant appear equal or higher with the MH but the MH has a lot more useful blues and blue-greens.
Summary and Zarnon's experiment: The MH appears to duplicate sunlight, be recommended as a primary light and have greater levels of useful light where it counts. I'm going to try an Agrosun with my clones all through flowering and see how they do! Stay tuned.
If you understand what the visible spectrum of light is (400-700) nm, then you will have an easy time following along. See previous post with links to basic concepts.
Plants use light as a part of photosynthesis, regulating rhythms etc. However, 'all light is not created equal'. Certain parts are more important than others. This includes the blue (400-500nm) and reds (650-680nm). This is where PAR gets off-base as it gives equal weight to this entire range (see previous post).
So what we're talking about is a 'plant sensitivity curve', right? A correct one would show higher levels of response to these two areas? Pic three and the link below are examples of them. There are also many wrong ones. Unfortunately these seem to appear a lot in hydro lit or MJ forums as well. The white line in pic 1 is an incorrect one.
(Another correct plant sensitivity curve from Univ. of Hamburg); http://www.biologie.uni-hamburg.de/b-online/e24/3.htm Note, two bumps at the distal ends of the spectrum (blues and reds).
Curve's differ, here's one for algae http://www.emc.maricopa.edu/faculty/farabee/BIOBK/pigment.gif
So is there a way to tell how my particular light breaks down? Color temperature is a good start.
'Color Temperature' is measured in degrees/Kelvin; The lower end is warmer (more reds) while higher is cooler (more blues). A HPS is 2000-3000k (3000 extended spectrum), while your MH can go from 3000-6500 (3000 also ex. spec). I've been able to find a color temp for all HID lights I've looked at.
Here are some examples of color temperature:
Sunrise/Sunset: 3200k
Halogen bulb: 3500k
Midday (sun overhead): 5500k
Overcast: 6500k
Shade 8000k
Blue Sky: 9000-12000k
We push 2000-3000 spectrum bulbs for flowering. Why is that? In the literature, a MH bulb is recommended if you have no access to sunlight while HPS are reccommended as a secondary + sun. Maybe it's b/c a nonextended spec HPS is creating a predominant red light, redder than a sunset and then intensifying it by a factor of ten.
I think of Kal-el on his balcony, checking out the Red Giant dominating the sky. Well, worked for Superman, surely Superbud?
Compare the spectral analysis for both. Pic 1 is HPS, 2 is MH. Compare both of them to an accurate plant sensitivity curve (pic 3).
Look at where they're going! Even the reds useful to the plant appear equal or higher with the MH but the MH has a lot more useful blues and blue-greens.
Summary and Zarnon's experiment: The MH appears to duplicate sunlight, be recommended as a primary light and have greater levels of useful light where it counts. I'm going to try an Agrosun with my clones all through flowering and see how they do! Stay tuned.