i stay with what i said as theres no space for if/but/maybe.
im not a liar unlike others roaming around here...
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Investing in new lights LED or HID?
- Thread starter repoocbd
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i stay with what i said as theres no space for if/but/maybe.
im not a liar unlike others roaming around here...
dizzlekush
Member
http://www.gavita.nl/v2/nl/nl/GE_lampen.shtml
I have seen multiple sources citing 1050 PPF as a typical output of a 600W HPS grow bulb. If we have a single source with an output of 1050 PPF, then at least we can't assume it will produce more than 1050 PPFD for whole canopy area if used on an area of one squaremeter?
Please bear with my noobish questions, I'm just learning about the basics of photosynthesis and plant physiology. I'd just love to have a deeper understanding of why things work as they do
IDK if a bulbs PPF is greater than its PPFD, PPF is a basic unit of light intensity (umol/s-1) while PPFD is the same unit with surface area added (umol/m^2/s). PPF is measured with an ulbricht sphere where the entire bulbs output is measured. PPFD measures the amount of photons striking a meter per second. When a bulb is placed in a reflector, its irradiance is focused on one area, and therefore increases. so again PPFD might be more intense than PPF. PPFD changes as you change the distance of the light source from the canopy, while PPF is the constant output from the bulb. I suggest you go ask knna or possibly whazzup the same question for a better answer.
Note- it seems that the term PPF is becoming interchangeable with PPFD more and more in academia and science as umols/m^2/s-1
Pn (net photosynethis) is measured in 3 ways that i know of:
CO2 consumption
O2 'evolution' (production)
Light induced delayed fluorescence [DF] (as plants photosynthesize, they emit small amounts of light themselves)
Measuring DF is considered to be the most accurate means of Pn quantification since it is the least likely to be effected by environmental factors.
This doesn't necessarily mean that 30% more Pn means 30% more biomass, but the group that has the highest Pn will always be the most productive (most phytochemicals formed, most biomass formed, fastest growth rates etc.)
Im sorry, im not following your logic. plants like heat. MJ wants it all the way up to 84-88F. They use L.E.D.'s in the experiment, specifically the "Licor LI-6400-02"
Wilkipedia? cmon bro, wiki is only good for the references.Wikipedia quote:
I hope I made some sense, very frustrating if I didn't
Hm interesting. you'll see that the test group that got 1000PPFD at 30C did the 2nd best out of all other experiment groups (better than the 1500ppfd at 25C and 35C) so maybe he changed his mind. I still agree with his old opinion that 1500PPFD is the best option, since all science agrees with that decision, but 1000ppfd will grow cannabis quite well.
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dizzlekush
Member
There is simply no way that L.E.D. will yield better G/KWh than a vertically oriented H.P.S. or that combinations of monochromatic light will produce more desired phytochemicals than full spectrum (with UV-a and UV-b) lighting. The 'increase' in grams per watt that you are noticing is true for ALL forms of lighting when you look at it like grams/watt/m^3. The lower the wattage you go, the more G/W/m^3 you get. look at the 4th study in my next post for confirmation.
Of course this is not to say that you haven't adopted a very effective way to cultivate cannabis with L.E.D.s. I've grown with L.E.D.s in the past and have seen your garden, and i admit that your L.E.D. garden is a very nice one, much better than mine was, and i had 540W of L.E.D.'s., but i was a complete amateur at the time.
dizzlekush
Member
Pretty sure its already been uploaded here, but just cuz you asked
I suggest you go back and read through the thread again. it is VERY informative and it seems like your prolly skipped over some of the good stuff.
https://www.icmag.com/ic/showpost.php?p=3248208&postcount=49
Here's a couple more studies for you not mentioned in the post above. The middle 2 measure the effects of different amounts of CO2 and temperature on cannabis grown at 1500PPFD (using the same Licor L.E.D. system). There were no signs in the studies that 1500PPFD was a saturation point for cannabis.
The last study shows point of diminishing returns when one looks at cannabis production as a G/W/m^3 equation.
Keep in mind that the last study was no where near optimal since the plants were not provided ANY nutrients aside from a starting nutrient charge provided in the peat. experimenters saw signs of light saturation at levels of 400W/m^3 which is ridiculous. Also only 250W and 1000W hps systems were used, placed at odd distances to provide the different 270, 400 and 600w/m^3. not actual 400W or 600W placed at normal distances from canopy. a silly study if you ask me, but ill upload it none the less.
PPF is like luminous flux, total output of the lamp in umol s-1 (total number of photons within PAR generated per second). Compare with lumens
PPFD is like irradiance, incident on a surface in umol m-2 s-1 so we add surface here (number of photons hitting a square meter surface per second). Compare with lux.
A 600W horticultural lamp does up to 1170 umol/s (400V electronic), an average lamp does about 900, a good lamp more than 1000. Now for the next calculation you need to know the efficiency of your reflector. Say you use a Gavita HortiStar then 96% of that light is really brought to your crop.
a 2000+ micromole 1000W lamp is capable of lighting a surface of 2.25 m2 with an average of 800 umol m-2 s-1.
The best uniformity in your room you get when you hang the lamps at more distance. The light levels will not be lower in an overlapping light situation, the penetration though will be a lot better. You lose light on your walls.
Growing cannabis at 1500 umol m-2 s-1 is possible, but it is not very efficient. You better spread this light over more surface to get a better yield. With CO2 you can go to a bit higher light levels, but without CO2 I would stick under 1000 umol m-2 s-1. Also it is much easier to control the climate when you plan your surface better, based on actual light output.
dizzlekush
Member
Hey whazzup, thanks for the insight. AFAIK a reflector that actually provides 96% of the bulbs total irradiance to the canopy is unheard of, the best ones (that cost over $500,000 just in design), provide about 90%. do you have any legitimate scientific empirical data to back up that claim? id really like to see that.
I agree with you mainly, but what is better is actually based upon your limiting factor. If its electricity, your statement is correct, if is grow area, then i gotta disagree and you want to get as close to 1500PPFD as you can.
oh yes our reflector is not something someone came up with on a lazy afternoon . It origins from our horticultural background, the HR96 design. Remember this is reflector efficiency: 96% of all the light is coming out of the lamp/reflector together, 1/3 of the total light is direct light from the lamp. The reflectivity of the Miro aluminum is not 96%. Always understand what it is you see specified. And yes, it did cost a lot of money to develop (and produce). It is hand made in holland and has a triple quality check for shape to assure optimal photometric quality.
If electricity is not your worry what is? It is already stupid that we have to grow indoors instead of under the sun, I like to use as little natural resources as possible to grow my own crop. I'm not a green activist or something, but I think when you grow indoors it is only responsible to try to do it using as little electricity as possible. But that's another end of the story.
If you are limited in space, then why overload your plants with light and create climate and plant problems when you could have done with a smaller lamp? I have seen people grow a great crop on 1.6 m2 with one 600W lamp, easily a gram per watt. The higher the light intensity, the more difficult it becomes to reach that gram per watt. Well, 1,5 gram per watt of course because a gram per watt is average these days. So even though electricity might not be your biggest worry, the well being of your plants should be on your priority list.
. It origins from our horticultural background, the HR96 design. Remember this is reflector efficiency: 96% of all the light is coming out of the lamp/reflector together, 1/3 of the total light is direct light from the lamp. The reflectivity of the Miro aluminum is not 96%. Always understand what it is you see specified. And yes, it did cost a lot of money to develop (and produce). It is hand made in holland and has a triple quality check for shape to assure optimal photometric quality.If electricity is not your worry what is? It is already stupid that we have to grow indoors instead of under the sun, I like to use as little natural resources as possible to grow my own crop. I'm not a green activist or something, but I think when you grow indoors it is only responsible to try to do it using as little electricity as possible. But that's another end of the story.
If you are limited in space, then why overload your plants with light and create climate and plant problems when you could have done with a smaller lamp? I have seen people grow a great crop on 1.6 m2 with one 600W lamp, easily a gram per watt. The higher the light intensity, the more difficult it becomes to reach that gram per watt. Well, 1,5 gram per watt of course because a gram per watt is average these days
. So even though electricity might not be your biggest worry, the well being of your plants should be on your priority list.
dizzlekush
Member
-Edit-
why is there no way? i dont understand. sure getting the right wattage per space will influence the gpw efficiency (whichever light you choose) but i dont understand how a well chosen LED spectrum cant be better than hps spectrum which was never chosen for plants. i grow the same cuts over and over again and have done so under hps and LED so i feel i can make a good comparison for taste/quality. i always presumed that the LED's were cooler and burnt off less terpenes than HPS for starters.
as for vertically orientated hps...the given reasons for why vert i s better were written by an estate agent im sure! i yield more in my horizontal hp setups than nearly all the vert grows ive seen. when it comes to hps i am a believer in good reflectors as the plants use the diffuse light from them very well.
VG
sx646522
Member
Hey VG. Still holding down the fort, I see. 
^This.
The dynamic equilibrium that exists between cannabinoid production and degradation at any particular period in the plant's lifecycle is heavily dependent upon changes in temperature (ΔT). This phenomenon tends to work in LED's favor.
That is in addition to other morphological changes that have been known to occur based on spectrum targeting, including using a disproportionate amount of (more damaging) higher-energy blue and far-blue light that is present in certain panels.
There are certain trade-offs to the latter, but some growers consider that to be a plus - on a net gain (quality, vs. yield) basis.
Slàinte Mhath, :friends:
-SX
^This.
The dynamic equilibrium that exists between cannabinoid production and degradation at any particular period in the plant's lifecycle is heavily dependent upon changes in temperature (ΔT). This phenomenon tends to work in LED's favor.
That is in addition to other morphological changes that have been known to occur based on spectrum targeting, including using a disproportionate amount of (more damaging) higher-energy blue and far-blue light that is present in certain panels.
There are certain trade-offs to the latter, but some growers consider that to be a plus - on a net gain (quality, vs. yield) basis.
Slàinte Mhath, :friends:
-SX
dizzlekush
Member
Well the warmer the environment, the faster cannabis grows (all the way to 88F), so your argument that L.E.D.s produce less heat for better growth is mute. Also your logic r.e. temperature and terpene loss does make sence, although its not necessarily true. what temperature woud you want your garden at to preserve terpene content in the plant?
Also its stated here (https://www.icmag.com/ic/showthread.php?t=211911) that you yield anywhere from .66-1.02 Grams per watt. I always try to not insult a grower who posts their pics, since i will not display such evidence myself, but you just said you yield more GPW than vertical growers.... even at your best 1.02 grams per watt, you're not beating too many vertical growers... heck according to 2 whazzups post a few back a gram per watt is average. better GPW than my L.E.D. run (by several hundred percent, shitty f*****g UFO's), not better than even my horizontal 600W hps grows.
of course because a gram per watt is average these days.
AFAIK L.E.D.s do not produce as much PPF per watt as H.I.D., they might have the deep reds and bright white's at a close enough range, but their blue, green, ~600nm and UV diodes are quite a ways off before reaching the efficiency of H.I.D. (which is only around 40% IIRC), and again as stated before, there is no known combination of monochromatic lighting that provides that quality of growth that full spectrum lighting (from an h.i.d.) does.
dizzlekush
Member
We were talking about volatile terpenes, not cannabinoids (non-volatile terpenoids) but interesting none the less.. you got any literature to back that theory up? or is it just that, a theory? i wouldn't think the diff. between 76F and 86F would result in that much terpene (or cannabinoid) loss, but maybe im wrong.
hi again dizzlekush, im not claiming that less heat produces better growth, that would depend on your ambient temperatures etc. what i am saying is that heat, especially radiant heat from HPS, will burn off aromatic oils and terpenes, which will effect the quality of your weed. i like to keep my garden mid 70 to mid 80 if i can, but as i said its more to do with radiant heat.
as for my gpw, it varies greatly as i do not usually grow commercial strains, and the moduar scrog method i use allow me to get an accurate gpw figure for each plant. with some of my more commercial cuts i can get 1.2 or 1.4 gpw, i would have to go back and look through my diaries for exact figures. there are very few strains i cant get 1 gpw out of, ive nearly managed it with bubba kush which is a low yielding strain for sure.
do you have a citation for your claim that a well chosen LED spectrum is not as good for plant growth as HID spectrum?
the reason why i swapped back to LED in my bigger cab was because i was convinced that the same cuts were better grown under LED than under HPS - the soil was the same for both.
also im finding that for a 8-10 weeks strain that they finish about a week earlier which also improved the efficiency.
VG
dizzlekush
Member
Why would i need such a thing? achieving optimal growth from L.E.D.'s is something scientists have been attempting for 30+ years, and so far it has not been achieved. show me 1, all i want is 1, study where BETTER growth is achieved with L.E.D.s that equal wattage of H.I.D. lighting. you might be able to find one that's trying to quantify the smallest wattage/m^3 that plant life can be sustained under.
People have been trying to kill other people with their minds for more than 30 years, you got a citation that its never happened? (a retired u.s. officer has killed 2 goats with his mind according to military records)
so are you saying that optimal growth CAN be achieved under HID lighting?
the LED lamp im using atm uses 187W in comparison with the 250hps that was in there before that uses 304 w. a year ago a similar wattage LED outyielded the hps in GPW but not in total yield. im hoping this time round i will get a comparable total yield from the LED - that remains to be seen... but on a yield per watt basis LED's beat hps for me a year ago and have likely got quite a bit better since then.
VG
the LED lamp im using atm uses 187W in comparison with the 250hps that was in there before that uses 304 w. a year ago a similar wattage LED outyielded the hps in GPW but not in total yield. im hoping this time round i will get a comparable total yield from the LED - that remains to be seen... but on a yield per watt basis LED's beat hps for me a year ago and have likely got quite a bit better since then.
VG
lol it's an interesting discussion. I won't mix into it but allow me to share a few observations.
In the greenhouse industry all LED experiments as a replacement for HPS as the main assimilation lighting failed. You also miss a lot of heat of course and need to add that energy. In fact we saw the same problem with the plasma lamp, temperatures too low for a healthy development when we did not extra heat the air. And of course it is still too expensive. We do see it used in layered growing methods and plant tissue culture a lot, but almost never for flowering, not even in lettuce. Plasma will neither replace HPS on the short term. Now you got to consider we are talking about greenhouses. They get the extra (quality) sunlight. Now we are very lucky that our specific plants love red light, because what they get indoor from just sodium is a really bad spectrum. I always favored a combination of (C)MH and HPS indoors, I had the best results with that. In Scandinavia in the winter, when the nights are long, the add extra metal halide in the greenhouses. It is a common rule that you need about 5-10% of blue light.
With increasing light levels in the greenhouses in the dark winters we see problems with plants in the greenhouses not getting enough blue light anymore. That's why from the greenhouse industry there is a lot of interest in for example plasma light. The Gan Lep was nominated for the Horti Fair innovation award last year and there are ongoing trials in research facilities.
During a recent summit with researchers and the lighting industry it was concluded that HPS is the lamp to beat for the coming years. They did though see possibilities for using LED as a steering light and interlighting in the greenhouse, propagation, vegetative growth and tissue culture.
There is a consensus that natural light has the best characteristics for plant growth. Now that's news isn't it.
I believe you can grow under led and get a good yield, but that requires a very good (and expensive) setup with many colors to get an optimal spectrum. If you can afford that by all means go for it. It's just a lot cheaper and easier to do it with HPS. I am sure that the best LED growers would get better results under HPS. But sometimes there are circumstances when LED is a better choice and for some it's just the sheer joy of using the new technology (I can totally understand that). Pioneering is always fun.
I don't think it is the discussion any more if you can grow under leds, but which specific products are actually well designed and based on a better spectrum and a better reproducible result. But that's more in knna's field.
But there is something else going on too. You can not always make a good comparison. Here is Europe many use horticultural European lamps which are available here as you can imagine with the bulk of the greenhouse industry concentrated in The Netherlands. They do not often use air cooled reflectors and are used to high output lamps. They stay away (the smart ones do) from copied Chinese (oem) lamps. The difference between output of two 1000W lamps can already be 30%! I think many growers here in Europe found pretty good ways to optimize their yield. They almost always use SOG and horizontal lamps in reflectors. I love big trees but they are not very practical to grow. Really good growers do 1.5 per watt.
</ramble>
In the greenhouse industry all LED experiments as a replacement for HPS as the main assimilation lighting failed. You also miss a lot of heat of course and need to add that energy. In fact we saw the same problem with the plasma lamp, temperatures too low for a healthy development when we did not extra heat the air. And of course it is still too expensive. We do see it used in layered growing methods and plant tissue culture a lot, but almost never for flowering, not even in lettuce. Plasma will neither replace HPS on the short term. Now you got to consider we are talking about greenhouses. They get the extra (quality) sunlight. Now we are very lucky that our specific plants love red light, because what they get indoor from just sodium is a really bad spectrum. I always favored a combination of (C)MH and HPS indoors, I had the best results with that. In Scandinavia in the winter, when the nights are long, the add extra metal halide in the greenhouses. It is a common rule that you need about 5-10% of blue light.
With increasing light levels in the greenhouses in the dark winters we see problems with plants in the greenhouses not getting enough blue light anymore. That's why from the greenhouse industry there is a lot of interest in for example plasma light. The Gan Lep was nominated for the Horti Fair innovation award last year and there are ongoing trials in research facilities.
During a recent summit with researchers and the lighting industry it was concluded that HPS is the lamp to beat for the coming years. They did though see possibilities for using LED as a steering light and interlighting in the greenhouse, propagation, vegetative growth and tissue culture.
There is a consensus that natural light has the best characteristics for plant growth. Now that's news isn't it
. I believe you can grow under led and get a good yield, but that requires a very good (and expensive) setup with many colors to get an optimal spectrum. If you can afford that by all means go for it. It's just a lot cheaper and easier to do it with HPS. I am sure that the best LED growers would get better results under HPS. But sometimes there are circumstances when LED is a better choice and for some it's just the sheer joy of using the new technology (I can totally understand that). Pioneering is always fun.
I don't think it is the discussion any more if you can grow under leds, but which specific products are actually well designed and based on a better spectrum and a better reproducible result. But that's more in knna's field.
But there is something else going on too. You can not always make a good comparison. Here is Europe many use horticultural European lamps which are available here as you can imagine with the bulk of the greenhouse industry concentrated in The Netherlands. They do not often use air cooled reflectors and are used to high output lamps. They stay away (the smart ones do) from copied Chinese (oem) lamps. The difference between output of two 1000W lamps can already be 30%! I think many growers here in Europe found pretty good ways to optimize their yield. They almost always use SOG and horizontal lamps in reflectors. I love big trees but they are not very practical to grow
. Really good growers do 1.5 per watt. </ramble>
interesting stuff, but as you pointed out - using a lamp as an addition to natural light is wholly different from growing under just that light.
so, correct me if im wrong, i thought that the spectrum emitted from hps, even 'horti' hps is far from the ideal spectrum for plant growth?
why then could LED not produce a better spectrum if you can pick and choose the wavelengths you want?
for example the LED i use has 6 wavelengths
440nm, 470nm,
525nm, 640nm,
660nm, 740nm
is that not any good? i though they were specifically chosen to be ideal for plant growth?
i believe it produces 1000-1200 umol at 12" which is about the distance im using it.
it seems to work really well, doesnt produce the ridiculous internodal distances that HPS can with some strains.
i have to agree that they are expensive, no getting away from that.
the heat thing - in winter they arent hot enough for the climate in my attic. all the rest of the year they are great, in summer they are a godsend
VG
so, correct me if im wrong, i thought that the spectrum emitted from hps, even 'horti' hps is far from the ideal spectrum for plant growth?
why then could LED not produce a better spectrum if you can pick and choose the wavelengths you want?
for example the LED i use has 6 wavelengths
440nm, 470nm,
525nm, 640nm,
660nm, 740nm
is that not any good? i though they were specifically chosen to be ideal for plant growth?
i believe it produces 1000-1200 umol at 12" which is about the distance im using it.
it seems to work really well, doesnt produce the ridiculous internodal distances that HPS can with some strains.
i have to agree that they are expensive, no getting away from that.
the heat thing - in winter they arent hot enough for the climate in my attic. all the rest of the year they are great, in summer they are a godsend
VG
oh yes you can make good spectrum with LED, especially the new white leds, but they are not so efficient yet. A very "spikey" spectrum seems to be a problem. If you add red, green and blue you get white light to the eye, but the plant sees spikes red green and blue. The white leds do a lot better with spectrum. Small bandwidth is a pro and a con: Until the LED it was very difficult to have good monochromatic light for experiments. Do not underestimate the necessity of green light either, especially at high light levels.
