Investing in new lights LED or HID?

[renz]

http://www.apogee-inst.com/pdf_files/SpectroradiometersEvaluatingLEDlamps.pdf

So from that doc, the RQE represents perfect absorption...

Explain why you dont make a high power LED array that mimics that?

MH/HPS isn't anywhere close to that profile. And why are you going to drop probably close to $10k on test gear and related equipment if the information is there, reflects common knowledge output curves for all the LEDs involved, and you're so sure?

You can make a lamp with that RQE profile and by your own reasoning it would kick the MH/HPS systems ass.

 

[SupraSPL]

@secondtry From what I have translated from KNNA's work, 1500-2000 umol/m2 is more of a maximum than an ideal target for cannabis. He suggests that a level of (300-400) evenly spread would be the most efficient use of power. I know you have posted a huge wealth of information and sources on this thread. After I get my assignments turned in I will take the time to catch up with what you posted, so I apologize if this was already addressed.

@cannaboy I agree that a vast majority of LEDs currently marketed as grow lights are questionable and probably a false economy compared to HID. But that does not mean the technology is "crap", far from it. Give it some time, there is a potential for significant cost savings as well as improved stealth.

 

[renz]

as well as improved stealth.

95% efficient 12VDC input boost mode current regulators, running of 12V car batteries, charged off mains at random or programmed rates and intervals.

It's not much harder to design than it is to imagine (well, for some of us), and it just doesn't get any more stealth than that.

 

[SupraSPL]

Maybe someday we can use high efficiency solar panels + 99% efficient AGM batteries to power the LEDs, as you said with 95% efficient buckpucks. Sounds crazy but it would be nice to be off the grid. I wouldn't be surprised if a system like that could pay for itself in a reasonable timeframe.

 

[renz]

Yes, someday.

LEDs won't make sense cost wise for a few years probably... unless you score an array that's working for you and that's designed to actually be a high reliability unit, and you manage to get years out of it, constant use (it wouldn't be surprising or even exceptional, at all, with LEDs as long as you don't drive them at absolute max current and/or temps).

Besides that exception, which maybe doesn't exist, HID kills it in terms of costs over the course of a couple grows or something.

 

[secondtry]

Hey there SSPL,

@secondtry From what I have translated from KNNA's work, 1500-2000 umol/m2 is more of a maximum than an ideal target for cannabis.

I agree over 1,500 PPFD is the light saturation range which leads to photoinhibition. However, 1,500 PPFD is ideal for cannabis (veg/flower) and over that irradiance ok up to about 1,600 PPFD but 1,500 PPFD is more ideal. I plan to shoot for 1,300-1,500 PPFD. I posted links to four differnst studies showing 1,500 PPFD offers peak Pn, and one of those studies showed the greater growth and yield under 1,500 PPFD (vs. lower irradiances). The peak PPFD outside near equaotr in late summer at midday near sea level is about 2,000 PPFD.

Also, umol/m^2 is not PPFD, it is PPF. We want to use PPFD which is umol/m^2/sec. That is one reason why the results from Knna's spreadsheet are not very accurate (conversion from watts to PPF, etc) and why I think they are not accurate enough to use (I reviewed the sources of his work and I asked Sanjay Yohsi about it; IIRC S.Yoashi suggested a probable error margin of > 10%).

SSPL wrote:

He suggests that a level of (300-400) evenly spread would be the most efficient use of power. I know you have posted a huge wealth of information and sources on this thread. After I get my assignments turned in I will take the time to catch up with what you posted, so I apologize if this was already addressed.

Ideal PPFD for cannabis is 1,300-1,500 PPFD. I would not want to grow with 300-400 PPFD. Many 400w HID's have PPFD values higher than that at 12" according to the finding of S.Yoshi, and considering 400w are hung 8-10" means the PPFD will increase (to a point). What does "evenly spread" mean? I will try to use the range of 1,300-1,500 PPFD because the footprint is a range of irradiance levels.


All the best

 

[renz]

I am looking for massive yields and I know I can get that with an HPS hydro grow.

So now I am looking for opinions thanks for any help.

Go with HID if you *need* results.

 

[renz]

(misposted to this tread, some mod delete this i cant figure out how)

 

[SupraSPL]

When I wrote umol/m2 I assumed it was understood that this was per second. I agree that 1500 will achieve maximum yields, but we should consider how much this yield will have been penalized by the law of diminishing returns. From what I am seeing so far, 300-400 is providing nugs that are big enough to be very easily and quickly trimmed (for most strains). So if increasing nug size with greater PPFD comes at a stiff wattage penalty, that would not be preferable in terms of efficiency. On the other hand, if growing space was more of a limiting factor than wattage, then I suppose maximum yield would be preferable.

When I say evenly spread, I mean if you are growing a short plant, LST SOG or SCROG, provide 300-400 to the upper canopy and spread it as evenly as possible across the entire canopy. The more evenly we can spread it, the greater efficiency we can expect. If you are growing taller plants, provide side lighting to the lower lateral canopy, still aiming for 300-400. This is achievable with LED as opposed to HID which might provide close to the saturation point to the upper canopy in attempt to "penetrate" to the lower canopy, which seems like a brute force approach that leaves room for efficiency improvement. It can be convenient to be able to customize the lighting to match the grow space.

Anyway, I am no expert, just trying to sort out the pros and cons that each technology has to offer. I will be able to offer some gram/watt numbers and smoke reports to work with soon.

 

[VerdantGreen]

How many people use LED arrays that close? (answer: very, very few) And considering the wallet I would never do that, talk about a tiny footprint! (how small is your garden? )


..... I plan to hang the LED array at a commonly used distance, ie. as is suggested by LEDGirl , et al. I will test the PPFD from the distance from which they hang their LED arrays, which seems to half a foot at least.


HTH

hi secondtry - LEDGirl only recommends the 6-12" from plants because light bleaching sometimes occurs with some strains at closer distances (which i thought was reassuring that they are chucking out some light). most people will run the led's closer than this providing the plants can take it. i ran my unit at about 4" because there was no extra height in the cab and had no problems. as for footprint, the lamps are not much smaller than the footprint they are used for. if you are measuring PPFD you need to consider this because HID cannot be put very close to lights whearas LEDs can be much closer and will give more PPFD at that distance.

V.

 

[asde²]

yo secondtry but 1500 is too much i think, 1100 is the maximum anyone should use with hps and considering led growers try to find the good spd the number will go down more
but colored led still lacks efficiency and whites spd aint that great keeping hid on top (but the future is near: http://www.cree.com/press/press_detail.asp?i=1265232091259 )

 

[secondtry]

Hey SSPL.

When I wrote umol/m2 I assumed it was understood that this was per second.

PPFD is always expressed with the second variable so it threw me when you didn't include it. I see what you mean now tho, thanks. However, Knna's figures/spreadsheet are still not usable because (IIRC) they come from lumen/m^2 and W/m^2 (what some call PAR irradiance) using McCree's work (vis a' vis the reefing work of Ivo Busko [1][2][3]) to find QFD (Quantum Flux Destiny; irradiance) and QE (Quantum Efficiency) of lamps in his spreadsheet. Using the method Knna did in his spreadsheet factors in too large of an error margin for me to be happy.

SSSPL wrote:

I agree that 1500 will achieve maximum yields, but we should consider how much this yield will have been penalized by the law of diminishing returns.

It's not really about yield, it's about the peak rate of photosynthesis (Pn), that is what 1,500 PPFD offers. We should strive to reach peak Pn, or as high Pn as we can, as a goal with lighting. Reaching and keeping peak Pn should be the main goal because it is what (basally) controls most all other aspects of the plant. The higher the Pn (to Pnmax) the generally better off the plant. While greater Pn doesn't equal greater yields as a rule it does seem to equate to an increase growth and yields of cannabis.

SSPL wrote:

From what I am seeing so far, 300-400 is providing nugs that are big enough to be very easily and quickly trimmed (for most strains). So if increasing nug size with greater PPFD comes at a stiff wattage penalty, that would not be preferable in terms of efficiency.

To me it's more than about yield, it's about quality and health of the plant. If you are happy with the nugs from your LED array that's great, but why be happy with something that could be potentially easily improved upon? If I am going to risk getting arrested I want do so growing the best cannabis I can, not simply growing cannabis while lowering my electric bill. Running a 1,000w in flowering is only like an extra $40-100 a month depending upon electric rates.

IIRC suggested PPFD levels for tomatoes are above what Knna suggests for cannabis...

• Oh yea, how did you measure the irradiance? How did you know the plants got 300-400 PPFD?

SSPL wrote:

On the other hand, if growing space was more of a limiting factor than wattage, then I suppose maximum yield would be preferable.

If wattage is not the limiting factor than one allows cannabis reach it's full potential, I don't think that's possible with LED arrays with lowsih [sic] irradiance of 300-400 PPFD.

SSPL wrote:

When I say evenly spread, I mean if you are growing a short plant, LST SOG or SCROG, provide 300-400 to the upper canopy and spread it as evenly as possible across the entire canopy. The more evenly we can spread it, the greater efficiency we can expect.

That is what I thought you meant. As in the homogeneity of the irradiance footprint? I wrote a post about this using S.Yoshi's data to make an example. I agree having a well 'spread' footprint is wise, that is why I prefer HID with a good reflector as it's makes a more even irradiance footprint, and a light mover is a great tool too. One thing about LED arrays I don't like much is the spectral footprint, I assume the range of wavelengths reaching each leaf will be lower than that of HID due to the reflectance properties of a good reflector and the spacing of different colored LEDs in an array.

Here is a post where I discussed these issues on a LED array vs HID basis:
https://www.icmag.com/ic/showpost.php?p=3244310&postcount=39

All that said, it's seems best to evenly spread 1,300-1,500 PPFD over the whole canopy, regardless of how the canopy is grown. That is why I like PPFD: the growing method is not taken into consideration (and it shouldn't be when comparing lamps on their PPFD and RQE). Cannabis photosynthesizes the most under 1,300-1,500 PPFD, thus we want to try and reach 1,500 PPFD when growing cannabis as long as we dont' reach light saturation from too much irradiance over the whole day (i.e. daily light integral). I know cannabis will grow at lower irradiance but why do so if it will grow better at higher irradiance?

SSPL wrote:

If you are growing taller plants, provide side lighting to the lower lateral canopy, still aiming for 300-400. This is achievable with LED as opposed to HID which might provide close to the saturation point to the upper canopy in attempt to "penetrate" to the lower canopy, which seems like a brute force approach that leaves room for efficiency improvement. It can be convenient to be able to customize the lighting to match the grow space.

I see are few issues with that paragraph:

The first being we want 1,300-1,500 PPFD everywhere we can offer it, but as you mention 1,500 PPFD at canopy will not be 1,500 PPFD intracaonpy. The goal of 1,300-1,500 PPFD is not to make lower buds large, it's to keep cannabis at it's peak Pn.

The second issue I see is a common misunderstanding of what happens to green photons intracanopy. Green photons tend to pass though the canopy (ex. diffusion) and they get bounded around between leaves until they are absorbed by leaf or lost, they are most often absorbed, not lost. That is a major reason why green photons can drive Pn more than red photons (there are more of them per second vs red and they get bounced around until they are absorbed). The fact the green photons reach intra and lower canopy means the old idea of "penetration by brute irradiance" is not needed if a grower is using a lamp with strong green irradiance, like the Horlitlux Blue. Green photons are quite amazing, the paper I linked to (the green light paper) discuses this, as do many papers I referenced on page 2.

FWIW: younger leafs and leafs higher in canopy have higher rates of Pn. That is one reason why using LST or topping to increase each plant's canopy area is wise.

SSPL wrote:

Anyway, I am no expert, just trying to sort out the pros and cons that each technology has to offer. I will be able to offer some gram/watt numbers and smoke reports to work with soon.

Cool. Although I don't think grower A's gram/watt (which should really be gram/kw/days) is relevant to grower B. Yield is affected by too many variables to use it as a way to judge the quality of a lamp, ie. LED vs HID. That is why we need (at least) PPFD because we know how PPFD effects Pn, growth, etc, of cannabis.


HTH


[1] "RE: PAR, Lemens, Watts, etc
http://fins.actwin.com/aquatic-plants/month.9903/msg00462.html


[2] "A Comparison Between Light Sources Used in Planted Aquaria"
http://www.aquabotanic.com/lightcompare.htm


[3] "Library of normalized spectral plots"
http://www.aquabotanic.com/lightcompare1.htm

 

[secondtry]

Hey VG,

hi secondtry - LEDGirl only recommends the 6-12" from plants because light bleaching sometimes occurs with some strains at closer distances (which i thought was reassuring that they are chucking out some light).

Yea for sure, light bleaching is commonly due to photoinhibition, but I wonder if it's very localized on leaf? (vs whole canopy leaf bleaching with HID).

VG wrote:

most people will run the led's closer than this providing the plants can take it. i ran my unit at about 4" because there was no extra height in the cab and had no problems. as for footprint, the lamps are not much smaller than the footprint they are used for.

Yea that is what I thought, it seems LED arrays don't scale well to growers who use 3x3, 4x4 and larger areas.

VG wrote:

if you are measuring PPFD you need to consider this because HID cannot be put very close to lights whearas LEDs can be much closer and will give more PPFD at that distance.

V.

Thanks for the info. I thought that was a common distance but I was not sure. What I mean by "reasonable distance" is if one has to place a LED array 2-4" from a canopy it makes the LED array less efficient when considering the area of the canopy irradiated by the LED array. What I mean is it seems that it would take more LED arrays than HID to cover the same canopy area with the same irradiance. Thus LED arrays (if the my previous statements are true) would cost even more to buy if a grower had a large canopy.


All the best

 

[secondtry]

Hey Asde,

yo secondtry but 1500 is too much i think, 1100 is the maximum anyone should use with hps and considering led growers try to find the good spd the number will go down more
but colored led still lacks efficiency and whites spd aint that great keeping hid on top (but the future is near: http://www.cree.com/press/press_detail.asp?i=1265232091259 )

Why should 1,100 PPFD be the maximum? And why do you think 1,500 PPFD is too much? SPD won't effect PPFD too much, please see my big post on page 2. The chlorophyll A&B absorption spectra should not be used to design a LED array, the PAS (Photosynthetic Action Spectra) should be used.

My problem with people claiming "we can make LED arrays match ideal PAS" is that if you are going to do that why not use an HID? The whole claim of LED arrays makers, originally and still is pretty much: "only the light plants use for photosynthesis is emitted", which is total BS, plants use all the PAR range for Pn and blue light has the lowest QE (Quantum Efficiency). Thus to offer the best light for plants we can use bright white light (because UV and far-rad are important) from an HID lamp with a good SPD (like the Hortlilux Blue). However, all that is assuming SPD is more important than PPFD and it is not considering the PAS is not anything like the chlorophyll A&B absorption spectra touted by LED array makers.

 

[secondtry]

...colored led still lacks efficiency and whites spd aint that great keeping hid on top (but the future is near: http://www.cree.com/press/press_detail.asp?i=1265232091259 )

What you (and Cree) mean by "efficiency" is not what I mean by efficiency. To Cree efficiency means watts to lumens, ex. "lumens per watt for a white power LED". To me (and photo-botanists) efficiency is really "quantum efficiency" (or relative quantum efficiency). Quantum Efficiency (QE) tells us how efficiently each photon within each wavelength within PAR range can drive photosynthesis. The greater the ability of the photon to drive photosynthesis the greater the QE of that photon's wavelength.

We need to measure the light plants use (PPFD), not the wattage vs the irradiance of light measurement for humans (lumens).

HTH

 

[Avenger]

If you know the luminous flux, and can measure lux, and have the SPD, can't you work backwards mathmatically to compute PPFD? Isn't that what KNNA's bulb analyzer tool does?


I mean a lux meter and a quantum meter use the same sensor don't they? They just use different filters on it to match the photopic or quantum response curve.

 

[secondtry]

Hey A,

Yes you can but it's not accurate (enough), there is no accurate conversion from that to PPFD, it's a big ball-park figure.IIRC according to S.Yoshi the error margin is probably > 10% (I asked him about Knna's spreadsheet). Another problem is comparing lamps when using different ballasts and reflectors. The ballast effects the SPD and luminous flux (as commonly quantified with a spectroradiometer) thus for an accurate comparison the same ballast and reflector should be used when testing the same wattage lamps. Further, the differences between spectroradiometers in terms of calibration, spectral response, absolute irradiance calibration, etc increases the error margin (e.g. normalization), thus lamps should be tested with the same spectroradimeter (which is what I plan to do). The irradiance reported on most (HID lamp) SPDs is often not by distance, and it should be by distance because distance effects the irradiance.

Please see this message from explaining these matters:

“What are the differences between Quantum Light and Solar Radiation?,”
http://support.specmeters.com/kb/index.php?ToDo=view&catId=13&questId=111

The range of wavelengths that plants use is called Photosynthetic Active Radiation (PAR). This is measured in units of micro-mol per metre squared per second (umol/m2/s) which is usually called Photosynthetic Photon Flux Density (PPFD).

At midday in mid summer the sun can reach around:

• 2000 uE = 2000 umol/m2/s = 9800 FC = 1060 W/m2 = 106000 LUX

Of course, this depends on the latitude where you live

From the above you might imagine that you could calculate conversion constants between them. However, this cannot be done. The trouble with comparing watts/m2, lumens, lux and umol/m2/sec (uEinsteins) is that it is like comparing apples with bananas with pears. Each system of units refers to different portions of the total light spectrum. So, to produce a set of conversion constants is misleading to say the least.

• The total solar spectrum is measured with a pyranometer in units of watts/m2 relating to light in the 400 to 1100 nanometer wavelength.

• Photosynthetically active radiation (PAR) is measured with a quantum sensor in units of umol/m2/sec relating to light in the 400 to 700 nanometer wavelength.

• Photometry is measured with a light meter in units of lumens or lux relating to light in the 380 to 770 nanometer wavelength.

As a matter of interest one mol/m2/sec is equal to Avogadro's number in photons: 6.02 X 10^23. This means that 1 umol/m2/sec relates to 602,200,000,000,000,000 photons reaching the earths surface in each square metre every second. That an awful lot of photons - maybe keep that number in mind next time you contemplate sunning yourself.

 

[secondtry]

FWIW:

Here is the work of Ivo Busko (who used the work of Keith McCree) that AFAIK Knna used to make his spreadsheet and much of the terms knna uses like "PUR":

[1] "RE: PAR, Lemens, Watts, etc
http://fins.actwin.com/aquatic-plants/month.9903/msg00462.html


[2] "A Comparison Between Light Sources Used in Planted Aquaria"
http://www.aquabotanic.com/lightcompare.htm


[3] "Library of normalized spectral plots"
http://www.aquabotanic.com/lightcompare1.htm

 

[mad librettist]

Quote:
SSSPL wrote:

I agree that 1500 will achieve maximum yields, but we should consider how much this yield will have been penalized by the law of diminishing returns.

2nd:

It's not really about yield, it's about the peak rate of photosynthesis (Pn), that is what 1,500 PPFD offers. We should strive to reach peak Pn, or as high Pn as we can, as a goal with lighting. Reaching and keeping peak Pn should be the main goal because it is what (basally) controls most all other aspects of the plant. The higher the Pn (to Pnmax) the generally better off the plant. While greater Pn doesn't equal greater yields as a rule it does seem to equate to an increase growth and yields of cannabis.


Quote:
SSPL wrote:

From what I am seeing so far, 300-400 is providing nugs that are big enough to be very easily and quickly trimmed (for most strains). So if increasing nug size with greater PPFD comes at a stiff wattage penalty, that would not be preferable in terms of efficiency.

ahem! 2ndtry, this was a bit of a gloss over. The law of diminishing returns is ignored at the grower's peril. It must go into the cost/benefit analysis.

Think of a canoe paddle. Your average canoe paddle is fine for a casual user. Now if you are out on the ocean doing 10 miles at least in an outrigger canoe, the 400$ paddle is stronger x2, lighter x2, and with a better shape x2. But the 1200$ paddle is maybe only twice as good as that, not 3x.

Pick any activity involving technology, and this law applies. It is inviolable. So saying we are not into yield, but into photosynthesis, is not an answer, it's a mental deflection.

what if the statement vis à vis yield is remade to address photosynthesis. We still have diminishing returns, but if I read you right, you are saying we are getting in there before the curve rises sharply?

I need to ask you again about 250w HID. Because that is probably my option A. I just gotta get off these nasty cfl bulbs.

 

[secondtry]

Pick any activity involving technology, and this law applies. It is inviolable. So saying we are not into yield, but into photosynthesis, is not an answer, it's a mental deflection.

No it's not. I was writing that the goal is to reach peak Pn, not yield, in terms of lighting. I also wrote yield is not raised with increasing Pn (as a rule) but in cannabis the yield does increase with PPFD. Like I have written, yield is not a good qualification for a lamp (ie. LED vs HID), Pn is the qualification we want to use. That is why McCree, Inadna, etc, didn't use yield when making their QFD (Quantum Flux Density) and YPF (Yield Photon Flux), and is the same reason not a single light plant measurement (I have seen) uses yield as a qualification or part of the equation; only cannabis growers do that

I don't understand the rest of your post, re: what you trying to get at with diminishing returns? Did you read my responses to SSPL already?

RE: 250 w HID:
What about it? I would use that with a good lamp (eg. Hortilux) and reflector (eg. PL) for sure, a digital ballast is a good move too. I think CFL should be called "Can't Flower Lights", CFL suck to grow cannabis, your gonna love growing with HID. Get an HPS for sure if Hortilux Super HPS comes in 250w. HPS has higher irradiance in general vs MH, but the Horlitlux Super HPS SPD is decent too, I have used 600w version for a long time. Oh yea, don't get a 'self-ballasted' HID, get one with an external ballast (heat issues).

HTH