Investing in new lights LED or HID?

[dizzlekush]

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.

VG

That is a very nice spectrum for an LED. the best growth ive ever seen in a study was from a mix of 455, 640, 660 and a green that i cant remember the nm of. Ratios are important though, red (640-660) to far red (740) for instance. can you post the amounts or ratios of the bulbs?

However the output of "1000-1200 umol" is confusing. do you mean 1000-1200 umol/s-1 (PPF) or umol/m-2/s-1 (PPFD)?

Either one is very hard to believe unless your unit is at least 400W.... but you might have me eating my words in a minute if the stats you provided are accurate and your unit is less than 600W. however for stats to be accurate, we need data from3rd party testers, not data from the company selling you equipment or competitors.

 

[whazzup]

The LEP has a ppf of 300 umol s-1. But when I measure close to the light source I can easily measure a ppfd of few thousand micromoles. However I do not get that on a square meter of course . When using lenses in LED you see the same thing.

 

[setaemies]

Again, wow! This thread has picked up some momentum Thanks Dizzle for the pdf's, I need to dig into them when I have more time. Thanks Whazzup for explaining the PPF and PPFD, I thought I had missed something important or misunderstood something very basic about light. Thanks to VG and sx too!

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)

We already have some blue and red LEDs surpassing the efficiency of the best HID lights, but of course they produce monochromatic light so theres no direct comparison. Only top bin Crees are available to the public, as Osrams can only be bought from group of bins. And sure as hell you don't see these being used in chinese made grow lights any time near future

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 there is something else going on too. You can not always make a good comparison.

Very well said whazzup! You can't deny the occasional success stories for example Mr.X and pinstripe on this forum. There are a shitload of factors that will influence the outcome of the grow and theres a lot to be found out about this new technology. We are somewhat comparing apples to oranges, because the nature of products we compare might need very different growing styles or environments.

I think I conclude this with my new favorite quote by A.A. Tikhomirov

I do not believe that we have to copy illumination of plants in natural conditions for use in controlled environment growing. ... Also, we should not strictly aspire to duplicating morphophysiological characteristics of field grown plants.

http://www.controlledenvironments.org/Light1994Conf/1_3_Tikhomirov/Tikhomirov text.htm

 

[SupraSPL]

Resurrection for debated topics

Resurrection for debated topics

Verdant I agree either HPS is burning off terpenes or the 450nm LEDs are causing the plant to create more. When I run the same cutting under LED and HPS there is no doubt which is stickier and stinkier. This is especially rewarding with Chems and OGs.

I have come to realize my HPS nugs are slightly leafier than my LED nugs (comparing the same exact cuttings). Same goes for outdoor buds and all-white LED grows, very leafy. I assume the cause is that white SPDs benefit from additional red and deep red. Whatever the reason, the reds and deep reds make for much better nug/leaf ratio.

Someone mentioned 88f as optimal for growth. I have found that as temps rise nug quality decreases and internode distance increases. Some varieties handle it better than others but generally the nugs are flufflier, less frosting, less flavor and they seem like they never want to finish (huge loss of productivity). 80-82f is the max I allow once the first few weeks of flowering has passed.

PPF and PPFD are essentially the same thing. PPF includes the word Flux, which means it does include surface area. PPF captures every photon from the lamp in 1 second so you can imagine an integrating sphere that has 1 meter2 wrapped around the bulb. PPFD and PAR watts are both very incomplete without knowing SPD. The PPFD of HPS and LED cannot be directly compared because the SPD is vastly different. Same goes for PAR watts.

PPFD is just specifying 1 meter2 of canopy. The number will never be higher than PPF of the bulb unless the light was focused into a canopy smaller than 1 meter2.

 

[SupraSPL]

LEDs have now surpassed the best HIDs in terms of radiometric efficiency. 600w and 1000w HPS top quality bulbs are thought to be about 40% efficient when brand new.

Driven at 700mA with a Tj of 50c
Luxeon ES 450nm deep blue M4R bin - 55%
Osram SSL 660nm deep red 4T bin - 48%
Osram SSL 660nm deep red 3T bin - 42%
Cree XPE 630nm red P3 bin - 42%
Cree XML2 4500K T6 bin - 43%
Cree XML2 3000K T5 bin - 40%

I am still skeptical about the value of UVA, UVB, far red and infrared and I do not include them in my DiY LEDs. Maybe it is possible to improve the SPD, but I can attest that they are not required and are not currently efficient. 450nm blue causes a response to increase anthocyanins and possibly terpenes. It turns stems and leaves purple without UVA.

Buddha Tahoe OG under 600 HPS:


Same cutting under Blue/White/Red diy LED:

 

[SupraSPL]

Dizzlekush, are you making the same argument as secondtry, that optimal Pn is at 1500 PPFD and that the law of diminishing returns does not apply? That argument is suggesting that increasing intensity beyond the value point yields better quality buds, and I have found that to be the opposite of what we see in practice. If it were true, I'd be on that bandwagon.

Of course we do not rate a light in terms of grams/watt, but that is the next logical step after PPFD/SPD. At the end of the day, grams per watt of the total system does matter and I have yet to see anyone make an effective argument that says otherwise. I run a cutting under 600 HPS and also under my diy LED. The LED outyields the HPS by at least 2X every time and the bud quality is higher. Those are objective repeatable results and I encourage everyone to try it.

 

[WindSnob]

ok this thread started in Feb 2010 and there is definitely an abundance of info here, but he was just wanting to know how to best spend his $400
So I'm just curious on what decision he made and what kind of result he had?

 

[yujin]

Well I can tell you if he only spent $400 on an LED the results would be pretty disappointing.
You simply cannot get good results from a $400 LED. The components you need to grow quality cost way more than $400.

 

[Small time]

Well I can tell you if he only spent $400 on an LED the results would be pretty disappointing.
You simply cannot get good results from a $400 LED. The components you need to grow quality cost way more than $400.

You do? Been doing great too. I must be doing something wrong.