I was skimming an aquarium website (in German!) and found this very interesting, yet incomplete, list of bulb/lamp comparisons. I have consistently found that those aquarium guys are way ahead of us with this kind of technical knowledge. PAR, PUR, Lumens, Lux, and Kelvin Light Efficacy Calculator I have only briefly played with the calculator, but I was using 1 x 1000W (the same numbers come up using 10 x 100W), 1 square meter with 1 meter depth and 50% reflector efficacy. Here is a link to some background information on how Quantum meters measure light in W/m2 and umol/m2/sec. Comparison of Quantum Sensors with Different Spectral Sensitivites I would love to find more stuff like this, so post your links to other studies, articles, tables, etc relating to Photosynthetically Active Radiation (PAR) and Photosynthetically Usable Radiation (PUR) as they relate to different bulbs, lamps, and LEDs. Lets keep this professional, technical, and scientific. Please leave opinions and Web bashing at the door. Travis
Note to Travis: Before you can dive too far in, you must acknowlege that plants use all visible light spectra in contrast to what you said in another thread or this discussion will not be in the least scientific.
He never said that. He simply asked if PUR leaves out green, he never said plants don't use green at all. Go ruin a different thread Swami. You aren't needed here.
Yes, Swami is correct when stating that plants use the whole spectrum of light. They even use some spectrums not visible, like UVB, which I found a UK reptile lamp company that offers these in a 54W T5 version (this will be my secret weapon if I can find it in the US): Arcadia 12% UVB While plants do use the entire light spectrum, we have to acknowledge the costs of trying to replicate the sun. If plants only use a small portion of the 500-600nm green spectrum, then I would rather find products that put their wattage towards the 400-500nm blue and 600-700nm red spectrums, as I have been seeking in this thread: Need help finding T5 High Output Lamps Similar to Nlites The point of or current discussion is simply to find more evidence of actual PAR/PUR values of specific technologies/products. The marketing gurus of most bulb/lamp manufacturers use lumens, lux, foot candles, and kelvin to delineate their products because most of their applications are for the visual spectrum of humans. It's time for gardeners to move away from the measures of light that unfairly weight in favor of our own sensitivity to the middle of the light spectrum. Travis P.S. Hey Lay. I know you were going to post some info in another thread when you found it. Could you post it there for reasons of a follow up, but also post it here. Thanks
So no one else finds this stuff interesting? Hmm. I'm still looking for PAR/PUR values for various light sources. Travis
I'm interested, but we already know what the best bulbs are to grow with, so it's mostly just an academic exercise to find PUR values and whatnot. My main area of research has been on light quality (spectrum), and how it controls certain plant responses. That area interests me more since it's something that is a relatively new field of research and something that is heavily misunderstood. This manufacturer is one of the only ones that I have ever seen that lists the PAR values of all of it's products. You may find something useful to you by looking at them. http://www.sunmastergrowlamps.com/WarmDeluxe.htm
http://www.extension.purdue.edu/extmedia/HO/HO-238-W.pdf That article has many interesting things in it. It mainly concerns DLI (daily light integral).
How much par light will a 65 watt led panel put off at 12 inches? I know par is measured in moles or micro moles, does that have anything do with nanometers? I know you need the par reading to be between 600 to 700nm or micromoles for flowering. Its a little confusing. I will look for more info. Any links would be helpful. It sounds like leds will be the future, I am still looking for side by side proof or some scientific stats comparing hps to led.