Drowning in conflicting plant graphs - help! (LED)

[RackitMan]

when you build your LED will you post up what you did. I am thinking of building one after summer. Start a build your own LED thread. Or I will. No, you do it. I am too shy.
peace. good luck with it.

Sure. Sharing is what it is all about.

[khyberkitsune]

"The most powerful model is 500watt but only draws 250 and is about 20 times brighter than a HPS 600watt."

Yea, no.

That's taking 2 watt diodes, PWM underdriving them to 1w to obtain a higher efficiency, but still output less than a dedicated full-power 1w module.

PWM = turn around and ignore it, you're about to get gypped for more equipment that does less. Those panels are PURE MARKETING and just to let you know NASA outright rejected any underdriven or even PWM overdriven panel.

[mrnobody]

I agree that the marketing is total bullshi&* but in all fairness any plants I have vegged under them and transferred to HPS are fat, many bud sites and full of resin. The proof is in the pudding and the smoke. There are hundreds of completed growdd with LED now some very very successful, some terrible. Just like with HPS or any other lighting medium. You can have the sun on your door but if you cant balance out air and water its pointless.

As for Plasma lights only drawing half the wattage to generate the same equivalvent wattage? How much does a HPS pull from the ballast? When you know that figure and when you know the figure then we can have a discussion. Just because something is 500watt it does not mean it uses 500 watts power! that bit should be basic science for anyone playing with currents!

The less aggro we can give each other on here the better. I am simply relaying information I was given by a reputable source. Admitantly he is trying to sell my his Plasma lighting but if its good enough for Chelsea Football CLub, Liverpool, Man Utd, Fulham and twenty more to grow their grass? I think its good enough for my plants. The sun on earth! Yes its going to involve some experimentation and dialling in but if you watch your plants they tell you everything you need to know!

[khyberkitsune]

Vegging is one thing, PWM will do fine there, but for a fully-LED grow, PWM is just not the way to go. If you're gonna get that kind of panel, you might as well put a proper 500w driver without PWM, pull the raw power from the panel, and just destroy a 1,000w HPS. There's no real point in trying to regulate the duty cycle in horticulture, sure there's a purpose for human vision (we're limited to about roughly 70-85 'frames per second') but to plants what matters is the overall umol output at a constant rate per unit of time. PWM won't allow that.

"500watt it does not mean it uses 500 watts power!"

Actually, yes, when something is rated as 500 watts, that means it draws 500 watts per hour, or .5kWh. It's not basic science, it's basic math and knowledge of the formula which gives that number. I build these panels for large-scale commercial horticulture operations, from Australia to Morocco. If you say it's 500 watts, I had better be able to plug in my kill-a-watt and it better register 500+w. If I see 325, I'm returning the panel. All of my other clients would do the exact same thing.

And even then, it's not the wattage that matters at all for growing lights, although the energy you use versus how much of the desired crop you produce is very important. It's the photosynthetic photon flux density. umol/m^2/s-1 is the primary concern for plants, with wavelength ratios being second place. Measuring by radiometric output is not helpful unless you have a ton of other backing numbers, or you can simply have the umol figure and be done with it.

"Admitantly he is trying to sell my his Plasma lighting but if its good enough for Chelsea Football CLub, Liverpool, Man Utd, Fulham and twenty more to grow their grass? I think its good enough for my plants."

Oh, so that's where those microwave induction sulphur plasma units I shipped a few months ago went. I heard they were going to be used in pitches.

That's right, I do those too. My actual professional title is Director of Research.

Oh well, they're out of my hands so what's said about them is no longer my concern.

But on a fair note, you'd get better performance out of a 15000K HQI Metal Halide lamp than you would my sulphur plasmas. Again, the high lumen rating is what makes it so powerful. In reality, the spectral output just isn't there, and the units are too heavy for my tastes especially as they get into higher wattage ranges (most of that bulk isn't electronics, it's a heatsink,) which is why I quit making them and moved to designing new things, like HID/Induction hybrids. HID light, fluorescent tube heat output. That's a couple years away still, we don't have strong enough diamagnetic materials to accomplish what's needed right now for re-focusing stray EMF back into a linear tube.

Targeted monochromatic is the way to go. As soon as they make QD phosphors for induction fluorescent and my new hybrid lighting, you can expect a 150w hybrid to smash a 150w LED unit. Pure focused spectral output peaks with natural trace outputs, at far higher photon flux densities. But, of course, that much light still means heat so no matter what ventilation is needed. Even LED panels claiming NO HEAT are BS. Room temp in my house, good airflow in the PC case, my temps in the case still shoot up to 85 from the LED panel. Thermodynamics is a pain, isn't she?

[RackitMan]

As you are the most knowledgable here, I have two more questions if I may.

1. I can find nothing in the science that suggests a 6 or 8 to 1 red/blue ratio. Is this just attempting to copy HPS/MH spectra or are there real studies that support this? On one advanced cannabis board (engineers not growers), the conclusions was a blue to red ratio of 1.5 to 1 is best, while the absorption graphs look like it should be closer to the inverse, but nothing as extreme as all of the popular LED lights.

2. As you stated, and I have come to the same theoretical conclusion, that it's the photosynthetic photon flux density that is most important.

Let's assume these mfg numbers are accurate for this discussion. If I have a white LED that outputs 100 lumens/watt and has a higher total PPFD than either a 75 lumen/watt red or blue LED, (sorry no spreadsheet) why would I not go with all white LEDs? The spectra is something roughly like 40% blue, 10% green, 20% yellow and 30% red. (Don't hold me to those numbers.)

Any light you can shed (no pun) on these topics would be greatly appreciated.

Thanks!

[RackitMan]

One more question for you, Khy. (Always one more. )

I was considering PWM so that I could save power for seedlings and early veg and use one light throughout the grow. During mid-late veg and flowering, PWM would not be used.

Is this OK or is it better to use the light full power for the whole grow and just raise it high up in the early stages so as not to shock seedlings - or just use another light source altogether such as CFL for the first few weeks?

As my space is small, a one light solution is best for me at this time.

BTW, I have a commercial 120w (1w LEDs) tri-color unit. While construction is very nice, the lumen output seems insufficient even for my 2' * 2' grow space based on my last grow.

[mrnobody]

Fair points it must be said and the level of information was very helpful but it would appear everybody has there say and believe me there are other professors, director of research etc people around. You didnt answer my question about a HPS 600watt. How much power does that use? Because if i rememer rightly it uses more than 600watt? Hence why digital balasts are claiming to use less watts? Or am I jsut mistaken as I am sure I can fetch the links?

And as I have said already we should be trying to recreate the sun? Full total spectrum. Plasma do this. Yes there are bulky models like Lumateks but there are also ones which are a lot smaller than a standard hps setup. There are grows dotted around that have been done, albeit badly, under Plasma and the results are great, even in a poor environment. Especially the plasma horticulatual light poles which strcitly speaking you could have standing right next to your plants therefore creating that light at canopy level i think we should be looking for. My aramgeddon under LEd veg hav no popcorn buds, they are dense nuggets right down to the soil, i have supplental led light horizntally streaming across my canopy level.

I am wanting to ditch HPS as soon as I can so am passionate about new lighting. Plasma seems the way forward with supplemental LED lighting.

Facts are as only as good as proven results. For twenty years we have been ignorant towards lighting and still that ignorance seems bliss.

Anyone else have views on Plasma or any links? What is about is scarce but fascinating.

[mrnobody]

Clive says let there be light, like the sun (From Echo)

[bigsby]

I'm no director of research - far from it... but my limited understanding tells me that plants do not use the entire light spectrum. In fact, it uses quite limited amounts of white, yellow, orange and green. So an HPS that pumps out tons of "white" light (not to mention heat) is wildly inefficient. It is successful due to the high photon flux rate across the spectrum.

Khyber get's crazy props for his in depth knowledge and understanding. We need to thank him for the time he puts in here educating nOObs like myself. I'm happy to address my next question to The Director.

I've seen these lights LEDs with dimmers and I've wondered why you would use them. OK, with young seedlings you don't need to raise the light if you can dim it. And I guess you could tweek them to better mimic sprning / summer / fall lighting but really, the major factor is time phase (12/12 vs. 18/4) so once your seedlings are into veg wouldn't you just crank the LEDs all the way up and leave them there to maximize output / penetration?

[stra8outtaWeed]

I'm no director of research - far from it... but my limited understanding tells me that plants do not use the entire light spectrum. In fact, it uses quite limited amounts of white, yellow, orange and green. So an HPS that pumps out tons of "white" light (not to mention heat) is wildly inefficient. It is successful due to the high photon flux rate across the spectrum.

Khyber get's crazy props for his in depth knowledge and understanding. We need to thank him for the time he puts in here educating nOObs like myself. I'm happy to address my next question to The Director.

I've seen these lights LEDs with dimmers and I've wondered why you would use them. OK, with young seedlings you don't need to raise the light if you can dim it. And I guess you could tweek them to better mimic sprning / summer / fall lighting but really, the major factor is time phase (12/12 vs. 18/4) so once your seedlings are into veg wouldn't you just crank the LEDs all the way up and leave them there to maximize output / penetration?

i have thought the same thing...whats the point of having a dimmer :wtf:

and i am in the same boat...just a grower with keen interest in new tech lighting