to put it in perspective: The percentage shows how much more light this lamp produces compared to the next lamp in the line-up.
That's a good question. I never understood PAR watts, but let me try to break it down for you. As far as I know Sunmaster uses PAR Watts. As they are the only or one of the few who use it it is hard to compare to anything else.
So though they acknowledge that ppf and ppfd are good ways of measuring light they focus on how much enery is converted by the lamp in the 400-700nm PAR spectrum. If I understand it correctly they measure the energy of the photons between 400 and 700 nm, but express that in energy.
The claimed highest PAR Watts unfortunately doesn't seem to correlate with high growlight output. Don't ask me why, I never calculate with PAR Watts.
12-17-2011 08:01 PM
Just to help clarifying this topic, both PAR Watts and PPF (Photosynthetic Photon Flux) are radiometric measurements of light output.
But plants uses photons, not watts, so the accurate and meaningful figure which most closely relates to photosynthetic outcome is PPF, in micromols of photons per second.
1 PAR watt of blue photons carries about 3.5 µmols while a red ones holds more than 5 µmols. More than 40% more photons for same PAR output.
It happens because energy of a photon is inversely proportional to its wavelength, so between 650 red photons and 450nm blue ones, there is 650/450=1.44, 44% more red photons than blue ones, or said inversely, there is 450/650=0.69, 31% less blue photons than red ones. And photosynthetic effect is related to number of photons, the excess energy is dissipated as heat into the leaves.
In order to avoid such confusion and use the figure more useful, as the most correlated with growth induced, botanist uses PPF and not PAR Watts, aswell as most manufacturers of horticultural bulbs.
Anyway, most HPS bulbs emits a very similar amount of photons on each PAR W, as their spectrum are very similar, ranging from 4.6 to 4.75 µmol/s on most cases (very blue enhanced bulbs can go a little lower, 4.51 for the Hortilux). Horticultural HPS usually are close to 4.65 µmol/s (4.66 on average for the Phillips GP).
So when having a PAR Watt figure from a HPS bulb, you can get a figure in µmol/s with small error margin, just multiply it by 4.65 and figure obtained won't by off by more of 1.5% of total. For example, say a HPS bulb emits 260 PAR W, then its PPF is 1209+-18 micromols of photons per second.
The Philips Agrolite XT is a good lamp and it can be used vertically. I am not an expert in vertical grows, but I think a combination with the MicroMole would be a good one (remember the agrolite was never built for electronic ballasts though!). I have no experience with the Solis-tek ballasts.whazzup,
Do you have any opinion as to which 1000w bulb/ballast combo may be best that could also be used in a vertical position?
I was thinking perhaps Phillips Aggro-Lite XT with a MicroMole or Solis-tek ballast?
That is a lamp that can only be used in European 1000W ballasts. They work on a lower voltage and are not that efficient in higher wattage, that's why in Horticulture we use 400V equipment and high voltage lamps.Is this the Gavita SE bulb tested in your chart?
Thanks.
(from Gavita website)
Gavita Enhanced HPS 1000 W
Brand: Gavita
Type: Enhanced spectrum HPS lamp
Power: 1000 Watt
Lumens: 130.000
Growlight (µMol): 1750
Voltage: 230
Wait a minute, now I'm more confused knna.
The energy of a photon is inversely proportional to it's wavelength yes. This means that short wavelength (450nm blue) photon is more powerful than a long wavelength (660nm) red photon. Blue light carries more energy, not the other way around.
Par Watts and PPF are the same thing stated in a different way. It's radiometric power in the range from 400-700nm, it's that simple. Par Watts and PPF are faulty mechanisms for measuring how good a light source will be for photosynthesis, because they weigh all photons evenly between 400-700nm, when plants don't see photons evenly, and neither do we.
That's why we have "lumens" which is a measurement adjusted to the sensitivity of our human eyes. "Lumens" gives green photons much more weight, because we're so much more sensitive to green than we are to red or blue.
YPF PPF is the true measurement of how useful a light source will be for photosynthesis, and unfortunately not used very often, or even known about outside of the professional lighting world. YPF PPF weighs photons in the range of 360-760nm according to photosynthetic response by the plant, just like lumens does for our eyes. It turns it into a useful meaning.
That is a lamp that can only be used in European 1000W ballasts. They work on a lower voltage and are not that efficient in higher wattage, that's why in Horticulture we use 400V equipment and high voltage lamps.
What was tested is the Gavita Enhanced 1000W E39 US lamp we are introducing next month after 1,5 years of trials. We postponed introduction 3 times because we wanted to improve certain elements, with this result.
We actually decided to stop selling 230V 1000W EU lamps as they are no match to the high voltage lamps.
.Using a 100W 555nm lamp will have the same PPF as an 84W 660nm lamp. A plant will however, grow much better under the 660nm lamp
@shafto: Please read my remarks: with ANY ppf measurement you have to take into account the spectrum. Comparing PPF is a good general tool.
I do not necessarily agree with that. They will both perform really bad because of narrow spectrum, specifically in a generative stage. You can easily do the test with LEDs. Also you need to take into account the efficacy of the lamp. 100W input doesn't mean 100 PAR Watt output.
I don't have all the answers, there is still much ongoing scientific research. Until there are more reliable sources we stick with PPF: that is the only way to measure full photon flux from lamps.
But still when red light outperform green light efficacy, how do you measure it in order to express it quantitatively on a index as YPF? For what plant? What CO2 level? What average irradiance?
What I meant to say is that I do agree with you that 100 micromoles of one color is not the same as 100 micromoles of a for example full continuous spectrum. If you compare lamps you can not always just compare PPF, there are other factors that define the quality of a lamp, specifically spectrum. You can not compare 300 micromoles 640 nm with 300 micromoles full spectrum light for example for effect on the plant. But that is not what we are measuring now.I did read your remarks, though I'm not sure what you mean with this "ANY ppf measurement you have to take into account the spectrum." The spectrum is stated, it's 400-700nm, that's what PPF is. Total photonic flux from 400-700nm.
If you just look at the chlorophyll response then only red an blue LEDs would be the perfect solution. I think we all know that that theory did not completely work out as expected.My example of green vs. red light would hold true, though obviously the plant would do poor under only red light, the red light is much more useful to the plant than green light, which you can easily understand by looking at any graph relating chlorophyll A or B response to light. Also, we're not talking about lamp driver efficiency, so why would you bring up 100W intput isn't going to be 100W output of light? Of course not.. but that's not what we're talking about here. Call it an imaginary perfect lamp if you want, or imagine they have the exact same efficiency and efficacy, it really doesn't matter, it's still a sound comparison proving why PPF is flawed.
Maybe not as good but it has a function. Take a look in the sunlight spectrum: there is a lot of green light in it and less red. That might explain why a plant uses it differently. I am a firm believer in full spectrum btw. HERE is an interesting read.PPF says that a green photon is as useful to a plant as a red or blue photon. Whazzup, would you agree that green light works just as well for growing plants as red or blue?
Some wavelengths have important signal functions. The fact that green light does not disturb your flowering cycles does not mean it is not effective. According to the McCree curve green is not ineffective. The reason why plants might not use it as they do with other light is exactly what knna explained. And there are plants with much different response spectrums and light recipes.People use green when lights are off for a reason, that plants don't see it nearly as well as red or blue (and we see green very well). Ever wonder why a plant's leaves are generally green? That would be because they mostly reflect green light, while absorbing red and blue.
Green photons are not as effective as red or blue photons for plant growth. PPF does not account for this.
Yes but a good measurement of what? And how would a lot of red light influence the score compared to ppf?YPF PPF takes into account the response the plant has to different wavelength photons, it's a better measurement, there's no argument here.