http://www.heliospectra.com/sites/default/files/general/What light do plants need_5.pdf found this article from one high end led makers. was a very interesting read
Lighting interesting article on plant light needs
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Yes its a very good read. Especially that you find references to the scientific sources.
If you have a closer look there is much to be learned if you also read into electrical efficiencies of light sources. It enables you to easily identify scams in marketing e.g. XY W of Led beat XYZ W of HPS.
If you have a closer look there is much to be learned if you also read into electrical efficiencies of light sources. It enables you to easily identify scams in marketing e.g. XY W of Led beat XYZ W of HPS.
unfortunately light makers use a lot of confusing terms that are not relevant to plant growth to mislead consumers and hide weakness in their product. the truth is that people have had good grows with every commonly used light source but each one requires a different growing style.I can not afford the expensive leds but have not been impressed with the performance of inexpensive lights. led technology is improving but hps lights and fluorescent have become much better too. I can't use HIDs in my grow closet because of heat issues but have had good grows with fluorescent. bottom line: do your research and use what works best in your situation. then use the proper style for that system. also keep in mind that these action curves are developed using mono chromatic lights and energy is converted from watts or lumens into quantum so that the equations will work. which skews the graphs. in the real world we work with radiant power
Heat is also strongly dependant on electrical efficiency.
An efficiency of 40% W PAR/W means it converts 1W of energy in 0,4W of photons used by plants and emits about 0,6W of heat.
If you have a kickass hps at lets say 33% and a 3W cheap chinese led run near its max of 2W it typically will be lower in efficiency than those 33% and if you use the same amount of Power:
This means the led would actually put out more heat than the HPS.
Main difference is how its perceived. HPS puts out a good amount of its heat in rays that directly heat leaves. The led mainly conducts its heat to the heatsink as radiant heat. Yet in this case the led would increase roomtemperature more.
If you still have your inexpensive grow light you could improve it to some extent by putting in a weaker driver. e.g. a 350mA driver instead of the typical 700mA drivers -if its a 3W led thingy.
An efficiency of 40% W PAR/W means it converts 1W of energy in 0,4W of photons used by plants and emits about 0,6W of heat.
If you have a kickass hps at lets say 33% and a 3W cheap chinese led run near its max of 2W it typically will be lower in efficiency than those 33% and if you use the same amount of Power:
This means the led would actually put out more heat than the HPS.
Main difference is how its perceived. HPS puts out a good amount of its heat in rays that directly heat leaves. The led mainly conducts its heat to the heatsink as radiant heat. Yet in this case the led would increase roomtemperature more.
If you still have your inexpensive grow light you could improve it to some extent by putting in a weaker driver. e.g. a 350mA driver instead of the typical 700mA drivers -if its a 3W led thingy.
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Im no mad scientists and have no proof but I see this HPS 33% PAR/W and LED 40% PAR/W, now what confuses me is that par is supposed to be the most accurate measurement for plant grow light? If so how comes most journals I read hps will yeild like .6g p/kw and led closer to 2g p/kw these are literally just guesstimates based on diff jornals I have read. Or old school way hps you will aim for 1g/w yet led your aiming for 2 possibly more.
Im not going by the cheap as chips led nor cheapo hps, talking better then average grows. Like I said im no scientist nor mathematician but either you confusing par/w to lumen/w or there is a very good chance that maybe par is not very reliable either or maybe my math is wrong? I don't know
Don't get me wrong I am not knocking any light source esp as right now I am using hps for temperature reasons and not complaining, but I just don't get it.
Im not going by the cheap as chips led nor cheapo hps, talking better then average grows. Like I said im no scientist nor mathematician but either you confusing par/w to lumen/w or there is a very good chance that maybe par is not very reliable either or maybe my math is wrong? I don't know
Don't get me wrong I am not knocking any light source esp as right now I am using hps for temperature reasons and not complaining, but I just don't get it.
PAR is the most convenient way and while not perfect its agreed upon in science as standard. Otherwise you would have to create a response curve for each individual plant and measure lightspectrum with a 3000$-20000$ spectroradiometer.
Can you show me some of those "2 gpw" oldschool 12/12 grow-journals? But then id be interested in a true average, not if 1-2 persons of 1000 say they have 2gpw.
What is your own experience -with same genetics? Same setup, just different light sources, same wattage -did your yields tripple-quadrouple? What kind of hps did you use 600W-1000W or 150-250W?
I will try if I can find the efficiencies of those 150W-250W hps, they are supposed to be quite worse then 600-1000W, by how much I dont know.
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also this is a very good read too http://envsupport.licor.com/docs/TechNote126.pdf
Can you show me some of those "2 gpw" oldschool 12/12 grow-journals? But then id be interested in a true average, not if 1-2 persons of 1000 say they have 2gpw.
What is your own experience -with same genetics? Same setup, just different light sources, same wattage -did your yields tripple-quadrouple? What kind of hps did you use 600W-1000W or 150-250W?
I will try if I can find the efficiencies of those 150W-250W hps, they are supposed to be quite worse then 600-1000W, by how much I dont know.
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also this is a very good read too http://envsupport.licor.com/docs/TechNote126.pdf
Will have a read when have time. Not sure why you have said about 12/12 grows, what I mean with old school gpw is when I started looking at growing a few years back people would seem to aim for 1gpw, before I go any further I think we all know this gpw thingy is very unreliable gpk/wh probably much better but anyways my point is 2gpw is as far as im aware pretty unheard of with hid yet im pretty sure with the right leds 2gpw is within reach and this par/watt figures suggest that the difference is not possible. Maybe I am naive but I have seen enough grows to believe that led probably can double the efficiency of hids. Like I said only really an opinion.
My experience doesn't really matter as im a rubbish grower as work does not allow me the time to care for my plants as well as I should meaning inconsistent results, I also only own a 70w, 150w and 250w hid and a 4 tube t5 and a crappy lil ufo. Although there will be a led using under 100w very soon just not sure which one finances allow.
My experience doesn't really matter as im a rubbish grower as work does not allow me the time to care for my plants as well as I should meaning inconsistent results, I also only own a 70w, 150w and 250w hid and a 4 tube t5 and a crappy lil ufo. Although there will be a led using under 100w very soon just not sure which one finances allow.
thermal measurements are the best way to measure light efficiency. for a given amount of input power the more heat a source generates the less radiant light it produces par is just a measurement of light produced in the 400-700nm range and is usually measured in lux or lumens. pur is a measurement of light produced in the red and blue spectrum with much less weighting given to the green region.only about 30% of the light produced by HPS falls in this region.leds may be more expensive but to produce a spectrum that is most useful to plants and target all their pigments without over driving any of them would be very expensive.the fact that HPS lights will increase grow room temprature more then the same wattage of led or T5 lights call into question their relative efficiency. HPS or MH may have been the best option 35 years ago but a lot has changed since then.most cheap leds are too heavily weighted in the red region and do to cost and heat issues.when the cost of good leds come down they may be a cost effective alternative.things like genetics and growing style have a very big impact on yield per watt.but breeders are coming out with better strains all the time so 2gpw may be achievable in the near future but looking at grow journals I do not see a significant difference between modern lights some people have gotten 1gpw with CFLs which are one of the most inefficient lights on the market. some of the very high power CFLs (250-300 watts) are no better than the old T12 shop lights.so the debate about lighting is probably going to be with us for quite a while.
minime, sorry I thought that that was what you meant by "oldschool".
YPF yield photon flux accounts for quantum efficiency of wavelengths but is much harder to obtain.
Its not as easy as it looks. And the latest development -double ended bulbs increased efficiency again -unfortunately delaying a decrease in led cost.
Dont get the wrong idea, I prefer led any day over hps. Not only can they be better in efficiency, but also is their light beeing emitted in the "right" direction. You can spread the light with several smaller panels much better over the canopy. Beeing more efficient heat is reduced, spectrum can be adjusted...
-I just wish people get more sensitive to OUTRAGOUS claims of panel peddlers.
You could have a look at CMH, while pretty cheap they are very efficient like big HPS. Of course led is a very good idea too. Depends on budget.
PAR measures the ppf photosynthetic photon flux. Lumens measures intensity based on human eye response curve (vlambda curve).
YPF yield photon flux accounts for quantum efficiency of wavelengths but is much harder to obtain.
PUR seems pretty useless to me, especially when looking at the paper you posted. Well it depends, I dont know if its based on YPF.
Well have a look at the billion dollar horticulture industry, they care for gaining $$$$$ by saving power big time.
Its not as easy as it looks. And the latest development -double ended bulbs increased efficiency again -unfortunately delaying a decrease in led cost.
Dont get the wrong idea, I prefer led any day over hps. Not only can they be better in efficiency, but also is their light beeing emitted in the "right" direction. You can spread the light with several smaller panels much better over the canopy. Beeing more efficient heat is reduced, spectrum can be adjusted...
-I just wish people get more sensitive to OUTRAGOUS claims of panel peddlers.
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veru interesting read found it interesting that converting from radiant power (watts) to umoles shifted the spectrum by a factor of 2 quantums are a heavily skewed measurement since it multiplies radiant power by wavelength and an arbitrary mass (one of many correction factors needed to make quantum equations work) theory is a great starting point but control test are needed to establish facts. theory alone is only useful for creating chock dust LMAO and theorist make errors because they do not understand the real world. this is why "uncle albert" could not defend special relativity against the rate of closer argument except to claim that relativity is incompatible with mechanics. these theories are a useful tool but no substitute for experience in the real word.this should be remembered when light makers try to impress you with "academic speak" that most people do not understand as that great philosopher SNOOPY once said " if you can't dazzle them with your brilliance than baffle them with your b.s"
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