Hey Everyone I posted a thread in "advanced growing techniques" a couple days ago, where I basically prove, at least theoretically, that 4400K bulbs provide peak wavelength where it needs to be in the red spectrum for veg (660nm). However, I did not get any responses and although I am not 100% certain about whether or not 4400K actually beats 2700K in real life, I decided to make a bold claim (which I can back up with science) to generate some responses hope that this isn't too out of line but I really need to know soon and being formal got me nowhere... Anyways please, someone who knows what he/she is doing drop some knowledge for me. Here is my research: http://forum.grasscity.com/advanced-growing-techniques/508951-hunt-best-bulb-bring-sun-inside.html Here it is summarized specifically for this question: This is the formula that converts Color Temp (K) to wavelength (nm). maxT = 2.898x10^-3 m K ...or in other words: Peak Wavelength(m) x Temp(K) = a constant 2.898x10^-3 Which is equal to: Temp(K)=2.898x10^-3 / Peak Wavelength(m) What I discovered is kind of a shocker, first I checked 440nm which is the best light for photosynthisis in the blue spectrum. For 440(nm): 440(nm) = 4.4x10^-7(m) Temp(K)=2.898x10^-3 / 4.4x10^-7(m)= 6586 Therefore the temp I need in order to hit 440nm (4.4x10-7m) is 6586 K no surprise there as it is very close to the 6500K bulbs available and advertised for vegging. For 660(nm): 660(nm) = 6.6x10^-7(m) Temp(K)=2.898x10^-3 / 6.6x10^-7(m) = 4390K All I have been hearing from everyone is that I want to get a bulb with 2700K or 3000K for flower. But according to this formula, which is based on sound science, if you are trying to hit peak photosynthetic activity in the red spectrum (660 nm) then you want a bulb that puts out at 4400K. In fact if you do this formula and use 2700K then your peak wavelength is at 1073nm well beyond the usable light for cannabis! What a waste! So what do you guys think?
I think you need to experiment with 2 plants of the same age/size under both conditions to see which is better then report back to us. I would defintiely follow the thread. Post pics.
i agree completely... i do remember reading something about color temp and nutrient uptake and it reccomends 2700k for flowering, but as we all know you cant trust everything you read... your formula does make sense though, I would love to see this put to the test
I will, you mark my words, but its gonna be at least 1 or 2 months before I will buy my second T5 ballast. Im still just on my first grow and I cant keep dropping money left and right on lights and such. Already just bought a whole 400W setup plus a 4' 4bulb T5 ballast...
Great work Clos3! Very interesting...any update? I'm shopping for my first T5 fixture and came across those PLL-55 T5 HO fixtures(2' 55w 5000 lumen bulbs). I'm stuck between one of those or the regular T5 setups (2' 24w 2000 lumen). I can't find 2700k bulbs for the PLL-55's, only 3000k. The regular T5 can be found in 2700k. If you look at the graph you'll see there is a big difference between 3000k and 2700k in terms of chlorophyll activity. Basically I'd like to know if the extra 3200 lumen I'd get from a PLL-55 4 bulb (19,200 total lumen) vs. the 8 bulb regular T5(16,000 total lumen) is offset by being forced to use 3000k bulbs. But you're theory is very interesting as 4400k doesn't show much on that graph. I can get 4100k in the PLL-55's too.
HA!! Basically saying, you do all the work and lemme know if I can benefit. although it's the truth. Just the #s alone won't prove anything. Only side by side grows w a control/ secondary to get %'s higher to prove theory. I'm sure alot of people would jump aboard if you document it, and show progress!
well the thing is 4500 is no longer red...its white/going blue....numbers add up but there must be something wrong since 660nm is red but 4500k is white haha EDIT: also 2700 obviously works bc its what were using...soo that means either the nm chart is incorrect or their is a conversion problem
There must be something wrong with the conversion your using.....the visible light spectrum is from 400nm being purple/violet to 700nm being red....anything above 700 isnt visible by humans and is considered infrared...anything below 400 is also invisible and considered ultraviolet rays
Im definitely just gonna be safe and ADD ALL RELEVANT SPECTRUM'S I CAN AFFORD that makes for some POTENT...DENSE...HAIRY...FROSTY BUDs..and NUGGETS!!!!! I Know for a fact that when I add 6500K to my 2700K it makes the bud danker. So IM SURE adding 4400K 45w CFL's to your grow would be even better for the FROST...POTENCY... DENSITY...ETC. Thanks for showing this study! This is just proving that a full spectrum is better than than a single.... WIAT.... I mean so is 4400K by itself better than 2700K and 6500K of the same wattage for flowering. or is it just a good additive.
OK i wanna clear up the confusion here. When i made my original post I was a new grower just learning about color temp and such. Fonzi is right that 4500K puts you at blue-white light and this was in fact the stumbling block of my "theory" or whatever. However not because of the science. The science is sound, straight from a physics book its us humans that are flawed. The color temperature scale is based on how things appear to the human eye. Basically I was assuming a direct correlation between color temps advertised on bulbs and wavelength of light produced which is not true. Its a little confusing still im sure but just know that I was wrong. Dont go out and buy some 4500K bulbs to grow weed with, if you need new car headlights on the other hand...lol go check out a dude by the name of CFLweasel if you want some real knowledge about lights.
Hey guys i just found this thread while doing some research of my own on color temp and wavelength correlation for my own grow. I have some information and insight which may prove useful to those interested in the effects of the different light. While it is true 4500K light will appear white to us, it is composed of different wavelengths in different intensities. What Wien's Law describes is that the radiation curve of different color temperatures of light will peak in certain wavelengths, while still containing the many other wavelengths of visible light, as seen below. From the graph it is visible that the 4500K light will peak at around 630nm, the wavelength of maximum photosynthetic activity as seen here: So while it may appear white to our eyes, that white color is composed of peak activity in the red spectrum with mixtures from the other wavelengths that make it appear white. From anecdotal reports of other growers, they have reported success with using 4500K LED light setups. So I agree while it may be our eyes or our perception that is flawed, photosynthetic activity is most stimulated under 4500K lighting compared to 2700K lights. HOWEVER, as 2700K lights do offer strong grows as well, and they do peak at around 1100nm (well into infrared) I think there may be light outside of the visible spectrum affecting the plant properties which results in desirable harvests. This interested me further, so I began looking at the effects that infrared light may have on plants. I found an ehow link which compiled scientific study results from infrared exposure on plants and found the following: Among the results of infrared exposure are premature/quickened blooming of flowers, faster stem growth, and as a result longer internode spacing. Some plants even require infrared light to bloom. In summary I believe 2700K lights have their own strong merits in blooming and growth (as a result of peak infrared radiation), but the addition of 4500K lights would further increase harvest by peaking light in the wavelengths of maximum photosynthetic activity. Thoughts and comments appreciated! Hope this thread still has some live users