Discussion of the pragmatic application of LED's

[SOTF420]

Penetration is great I have never had any issues with a lack of it but then again I have not flowered with any mediocre low powered LED lights like many who have had poor results have used. Reflective materials on the sides of the canopy obviously are of great benefit just like with HID so they bud pretty much all the way down and benefit from all the reflected light going back into the garden. Those plants are like 3 to 3.5 feet tall in drip hydro using coir & hydroton mix. CO2 at around 1200 ppm.

I feed the whole time the lights are on and flowered those with Advanced Nutrients Connoisseur 2 part at around 900 to 1200 ppm with the added basic beneficial's from their line-up. They also got a couple scoops of the Fox Farm 3 part bloom boosters during flowering at the appropriate times added to the AN mix, the last 10 days flushed with RO water. Yield fully trimmed up & dried was right at a pound give or take plus I clipped a branch or two early. My girlfriend also ate a big bud at around 6 weeks flowering because she said it smelled like candy lmao. So considering the added small T5's in the corners the yield was still well over a gram per watt total with 8 weeks flowering time. Works for me.

 

[smokefrogg]

i'm drooling over the kessil lights, their densely packed led arrays sure sound sexy, curious how they'd be in application though

Instead of individually wrapped LED chips, Kessil applies a brand new platform that densely packs many of them together. For example, our H150 grow light uses a dense matrix platform that carries 21 LED chips in a circle smaller than a dime!

 

[SupraSPL]

GMT I would argue that "better results" is relative. Micro grows are one example where HPS cannot do the job as practical as LED. As far as vegging LED can outperform fluoros by 2X-4X. I am talking about DIY LEDs though, not much confidence in most prefab LED's radiometric efficiency.

I agree with the temp range 75-85f for quick finishes, good yield and density. I experimented with known clones in cold flowering ~50-60f and yields suffered as well as finishing time. When I tried warm temps 90-100f the same problems showed up, fluffy buds that take forever to finish plus a lack of frosting. The canopy temp range is critical. 75f-85f seems to be the sweet spot for me.

I have found no need to supplement infrared but a cheap option would be an incandescent flood rather than infrared LEDs. From what I recall incans output 95% infrared and 5% visible light. If daytime canopy temps are below 75f then maybe HPS would be a better option for that season?

UV does contribute to amber trichs which is lacking in LED but I don't miss it a bit. I tried flowering with and without UV-B reptile fluoros and the difference was negligible for me so I don't bother with them anymore.

The next thing I am trying to sort out is spectrum. I have tried 450nm blue + 635nm red + white with great results but now I am trying 635nm red + 660nm red + white to see if I can get better color mixing. If I were a good scientist I would not have made both changes at once but if I get too much stretch or a slow finish that should be easy enough to spot.

 

[knna]

I'm all for pragmatism.

The tests that have been carried out have shown that in flowering, better results can be achieved with hid bulbs than leds, and thats before you compare the cost per gram of bud.

The most practical useage of leds is in the veg cycle, but fluros do the same job, for the same if not lower power bills. And the cost of fluros are significantly less than leds.

So theory asside and concentrating on pure pragmatism, there are better options than leds for growing with.

Notice that this thread pretent to absolutely avoid that question.

Many of us are working more thinking on the future when LEDs will be the best option for price too. The purpose of this thread is LED growers can share their experiences and benefits from other's findings, so we can improve results of LED grows. It dont mind if they are cost effective or not. Almost sure that on the situations where they are not, they will be at some point of the future (probably near future). I would address this topic, as I have done in the past, but on any other thread except this one.

All I can say is that in general people of our group using LEDs after having used HIDs are getting double yield per watt used in average. And that itself is enough to keep working on it.

 

[yesum]

Maybe my wording wasn't very clear. The math takes into account 2 grows. If I get seeds started in the next 5-6 weeks, then I will have time to sex, clone, and flower...then clone and flower again before the lease on my apartment is up and I move.

Thanks for the response. Do you have the 126W light from Hydro-Grow?

I just found one of your recent posts. You grew this under LED light??? Very nice looking plant. It's hard to tell without a size reference in the photo, but that looks very similar to my results under 250W HPS, which is exactly what I hope to achieve with LEDs.

That plant was grown under 2 63 watt Hydro-Gro LED's. Each plant, 5 of them, yielded around 1/2 oz. With defoliation at first flower, I guess I would have gotten 3/4 oz each. 126 watts or so is good for 2x2 foot area.
Lower nugs were popcorn and the plants were 20 inches tall or so. I am supplementing next grow with vertical 55 watt pll in center of grow, for those lower nugs that did not get enough light.

 

[guest456mpy]

With all due respect to all of the posters I am asking everyone to stay on topic, that is the practical application of LED in regards to growing. Concretely, that means that I very much prefer to let other threads cover the topics of LED vs any other source; or one manufacturer vs another.

Thanks for keeping off of these particular subjects as they tend to be "hot buttons" which cause arguments and are not conducive to discussion.

Thanks again!
H.G.

 

[guest456mpy]

I'm all for pragmatism.

The tests that have been carried out have shown that in flowering, better results can be achieved with hid bulbs than leds, and thats before you compare the cost per gram of bud.

The most practical useage of leds is in the veg cycle, but fluros do the same job, for the same if not lower power bills. And the cost of fluros are significantly less than leds.

So theory asside and concentrating on pure pragmatism, there are better options than leds for growing with.

I will not dispute what you say, but counter with this.

Most if not all commercial builds of these lamps are designed to turn a profit. As such one cannot expect top binned emitters, nor designs that have not been compromised by manufacturing and financial concerns. The fact that we are just now reaching the "takeoff point" on the exponential growth curve means that the cost vs performance ratio is not such as to give rise to more robust manufacturing examples.

Having build my own top binned emitter based units and testing them against commercially available units I can assure you that there is an order of magnitude difference between a properly designed and constructed unit and those commercially avaiable at the present.

Weezard has built some units using 15 watt emitters. The light being produced by his example is already starting to cast a light field that is as strong as a 400 or 500 watt HID (I'm sure he will correct me if I am mistaken.) Look at the effects that the inverse square law has on a source that must be placed several feet further than the common source to target distances specified by today's commercially available designs. Add the fact that by the next cycle of products predicted by Haitz's law we will have surpassed the beam intensity of HID as long as top binned emitters are used in the build.

So in closing, let us focus with two main points of discussion:

1) What can be accomplished with the existing technology

2) Using Haitz's law to project into the next two generations of emitters, what does one expect to change and how will it change the ways we presently use LED's to grow.

 

[guest456mpy]

Point 1) What can be accomplished with the existing technology

Let's examine the inverse square law and how it can be applied to growing.

Any point source which spreads its influence equally in all directions without a limit to its range will obey the inverse square law. This comes from strictly geometrical considerations. The intensity of the influence at any given radius r is the source strength divided by the area of the sphere. Being strictly geometric in its origin, the inverse square law applies to diverse phenomena. Point sources of gravitational force, electric field, light, sound or radiation obey the inverse square law

.

The source is described by a general "source strength" S because there are many ways to characterize a light source - by power in watts, power in the visible range, power factored by the eye's sensitivity, etc. For any such description of the source, if you have determined the amount of light per unit area reaching 1 meter, then it will be one fourth as much at 2 meters.





So if at point R on the illustration above we measure the amount of light we need for "best" growth at point 2R we will measure 1/4 of the light needed for best growth.



So I propose to the group:

1) What does this have to do with penetration?
2) How can we use this law to plan our grow?

H.G.

 

[knna]

A few observations using high powered LED's for flowering regarding yields:

Results are far better yield wise with strains that have a good amount of early stretch during flowering initiation. I would grow a Indica/Sativa hybrid as opposed to anything mostly or pure Indica under LED due to the fact that plants are far shorter and more compact under high powered LED compared to those grown under traditional HPS light.

Good observation. But we have grown too squat indicas with excelent results, but adapting to pass them to bloom a little later, to counteract the lower strectching.

On the other hand, it resulted on very crowded canopies. Good results in this situation appeared when using side lighting. Some are trying defoliating when using just top lighting. We will see how they turn out this way.

Using side lighting, we have yielded over 3ft tall plants with good buds along all the height, and this happen more with short stretching indicas than with lenghty sativas, that tends more to have the good buds only on top colas or the end of lower branches.

I cannot speak for other brands (and there are many good ones out there) but this is what I have found flowering with the Lumigrow light. The reason it is important to note this is because LED spectrums can vary greatly and what is true for one grower may very well be opposite for someone using a different light so I am trying to be a specific as possible in that regard.

Thats why I say that is good to know what lamp is using each grower reporting something. Only way to fine tune spectrums is to compare results of each.

We try to not only compare spectrum by its qualitative results differences, but we try to check the spectral efficacy of each, in terms of yield por unit light delivered (independent of watts used).

As for the moment, Ive checked that there is no an unique optimal spectrum. I would like to emphatize this. Not only some strians does better with some spectrum and others with different spectrum, sometimes with huge differences.

Same strain may do diferentially depending of the irradiance used. At low irradiances, spectrums with dominant red, some blue and only a little of other wl does very good (but some strains dont go fine into bloom this way). While at high irradiances, trend is very different, with spectrums with a good percentage of white LEDs (thus more green-yellow) does same or better. Never worse.

This fact has convinced me of the need of using a good number of white LEDs if wanting to have a LED lamp able to bloom in a variety of conditions. Its possible to use little white (and none!) on some conditions/strains, but in general it not work fine on a variety of conditions.

When I say white LED you can put perfectly any other broadband white light source, as fluorescents. Ive been unable to find any noticiable difference between results using white LEDs or fluorescents when percentage of white is similar.

I tend to use more white each day I check results using it or not. On some conditions is possible to obtain a better spectral efficiency using less white, but in general, more white means a guarantee of good results.

Also, I have found yields are much higher in a hydroponics set-up as opposed to soil when using LED lights. Usually this is true for HPS growing as well (in most cases) but have I seen a marked difference in budding when growing under LED. Soil plants did okay nothing great but not bad either. But in a hydroponic drip system in a coir & hydroton mix the plants really took off and grew massive towers of dense high calyx to leaf ratio flowers. The plants in soil as expected were far more leafy and yielder far less actual dried bud.

Fully agreed.

Its not that LED on a soil grow cant work excelent. It can. MrX is doing wonderfull in soil with chinese LED lamps. But he is an excelent grower, I believe he could grow MJ with candles.

In general, people with better results are hydro ones. I do not grow in soil since many years ago, I have way better results on it whatever the lighting.

Some soil growers that passed to LEDs has changed to coco coir after a pair of grows. Soil is way more sensitive to keep the right moisture in it, and reduced transpiration and water uptake of LED grows makes more difficult to achieve the right dry/wet cycle. Hydro mediums are way more tolerant to it (I keep coco permanently wet, except for seedling and clones just rooted) thus the average grower get better results on hydro.

But I feel that its possible to do it well on soil too, but soil grower needs to find the right way of achieving it.

During flowering I supplement with a 6400k color temperature T5 light strip in the corners of the tent to give addtional spectrum to the plants that is lacking from the LED. This includes UV & Far Red. I would like to also note I plan to try a new far red LED screw-in bulb that just came out from Lumigrow. I cannot speak as to it's effectiveness yet because I have not used it but from the way it looks and research I have done regarding this, it may be a very welcome addition to bringing up yields and flowering responses under LED.

As told before, I dont notice differences between suplementing with fluorescents of white LEDs.

I was very concerned about how much far red to use at the beggining. We decided to start without it in order to check later improvement with it. But we found that result were excelent without any far red suplementation. At least, cannabis seems to require very little far red.

¿Can we get huge improvements adding more far red? I dont know, I would like opinions of people that have used it (I dont mind if with far red LEDs or incans, halogens, etc), especially when using white sources that already emits some. But I feel that it dont worth, in terms of energy input vs reward.

My conclusion may be a little partial because we use mostly 635-640nm red LEDs, and when using 660nm, its just partially. Maybe with strong 660nm lighting, the added far red worth.

All in all, I am glad I switched over from HID and do not plan to ever go back! For flowering I like 80 - 85 F as well it seems to be the perfect temp range with CO2 supplementation which I also highly suggest for flowering under LED lights it helps to maximize photosynthesis and will bring up your yield signifigantly. Grow on!

Agreed too. I do not have CO2 system and none of the member of out test group neither (well, there is 2 new that does). But on the paper, its a good combination.

Im only afraid that the increased water use efficiency with CO2 enrichment coupled with the reduced water uptake due lower overall temps and lack of IR result on the need of use too high ECs and possible deff of calcium (I would say that nutrient solutions with enhanced Ca content is going to be required on this scenario).

Hempyguy, I used my avalaible time on this post, but I want to explain some thing about beam angles, inverse square law and such. I believe its a topic not well understood at all. Maybe tomorrow

 

[Weezard]

Good questions?

Good questions?

Point 1) What can be accomplished with the existing technology

Let's examine the inverse square law and how it can be applied to growing.
.

The source is described by a general "source strength" S because there are many ways to characterize a light source - by power in watts, power in the visible range, power factored by the eye's sensitivity, etc. For any such description of the source, if you have determined the amount of light per unit area reaching 1 meter, then it will be one fourth as much at 2 meters.





So if at point R on the illustration above we measure the amount of light we need for "best" growth at point 2R we will measure 1/4 of the light needed for best growth.



So I propose to the group:

1) What does this have to do with penetration?

Obviously, a source that must be 1 inch from the canopy to saturate will be at 1/4 of saturation at 2 inches.
While a source that saturates at 2 feet will be 1/4 saturation at 4 feet!

2) How can we use this law to plan our grow?

H.G.

Aloha HG

Zackly why I used 15W. emitters in spite of lower electrical efficiency.

Top-bin, low-power emitters are great for SOG n SCROG but I wanted to grow a few mini-trees just for old times sake.
Ledengin emitters are the "brute-force" solution that fit my budget.

I have also found 60 degree lensing to be an acceptable "loophole" to the ISL on lower wattage emitters.

Tiny parabolic reflectors work very well, and plastic lenses are acceptable, in spite of some transmission loss.
(You gain more than you lose.)

The most common error in the use of leds for growing now is having the light too close to the canopy.

Saw one grow that failed because the light was so close that growth simply halted.
So he moved the light even closer for a while to "fix" that, then ripped it out in disgust and declared that "leds do not work".

Conclusion jumping can be a dangerous sport, yah?

Anyroad, that's my 2 cents on it.

All things are possible, given time and thought.
Weezard

 

[guest456mpy]

knna, my friend, I have a feeling I know what you are going to say about inverse square laws, multi-point lighting vs single point, etc. And I think I will already agree, but let's wait for tomorrow for that discussion, shall we.

Keynote here is pragmatism vs complete accuracy in calculations. I believe that there may still be some general conclusions that we can use from the formula.

Until then rest easy if your circumstances allow it !

 

[guest456mpy]

Darn, Weezard!

You slipped that reply in while I was typing.

Allow me to digest it ( and turn my sausages before they burn) before I reply!

 

[guest456mpy]

Back! (I couldn't help eating one of the sausages that were done before returning)

I'm not gonna bullet point each and every statement because you and I are in complete agreement in this particular respect. I almost wish you hadn't replied so quickly to allow some of the gears turn in other people's heads, but I must say I would have done the very same thing you did by replying quickly.

There were quite a few people in the last six months who asked me to help them build a LED system, but yours is the build I've ever seen. Would you consider starting a thread to assist DIY builders?

 

[SOTF420]

Does anyone know of a reasonable explanation as to why buds grown under LED seem to have more plentiful & more fully developed trichomes with seemingly more potent & more flavorful end results?

I have postulated it's a lack of excessive Infared heat, & UV radiation that would be present with most HID situations. I think under a high intensity HID grow some of the active ingredients such as THC & various aromatics, terpenoids, ect are lost due to degradation from the exposure of the plants to the above mentioned.

Unless I am imagining things, bud is more potent grown under LED.

 

[guest456mpy]

SOTF420,
I have noticed the same thing concerning potency and flavor. Alas, I have only theories and no substantiation. Give me some time and I'll try to express them.

In the meantime I'm sure others have their own ideas and concepts.

And I'm gonna eat some sausage and beer. Yum!

H.G.

 

[SOTF420]

Yes would be very interested in what people have to say about it! Weezard where ya at?

 

[Weezard]

I'm right behind ya, brah.

I'm right behind ya, brah.

Us 'zards get around.

Does anyone know of a reasonable explanation as to why buds grown under LED seem to have more plentiful & more fully developed trichomes with seemingly more potent & more flavorful end results?

I have postulated it's a lack of excessive Infared heat, & UV radiation that would be present with most HID situations. I think under a high intensity HID grow some of the active ingredients such as THC & various aromatics, terpenoids, ect are lost due to degradation from the exposure of the plants to the above mentioned.

Unless I am imagining things, bud is more potent grown under LED.

Imagination is not mandatory in this case. :-}

Got a few theories 'bout dat, and you nailed it.

Dunno much about the IR, but I have been playing with the UVb fo' a while.

Upon inspection with my Eyeclops, I noted that clear trich tops never "amber".
Makes sense, UV and IR mostly pass right through.

IR has a higher refraction, UV has lots more energy. Hmmmm?
But, I digress.

When they cloud up, they absorb both.
From experimentation, I found that it is the UVb that toasts the lil buggers.
Grew some outdoors, under a UV filter, as a control.

What I saw in my daily 'scopings was quite illuminating.


The natural progression is;
clear - cloudy - amber- dark n shriveled - absent.

As caps toast, the toasting appears to be way faster than linear.
Again, makes sense.
Darker = even more absorbent, yah?

So, once they begin to darken, they go from brown, to black and gone, in the blink of an Eyeclops.
All the while, the plant is producing more clear caps to replace the casualties until senescence or fertilization.

Under Leds, with no UV or IR, the cloudy caps begin to pile-up when their elders don't fry-off.


Then they also cloud up until you have a magic carpet.
Jus' look at dem pearls.




When the entire leaf is coated with cloudy trichs, I take them into the sunlight and watch them closely.

Depending on the day's UV index, they can tan in as little as 4 hours.
So, I keep some cloudy, and dry them inna dark.
The rest get tanned for 2 to 10 hours and marked with the tan time, then dried and jugged.


My claim?

The result is, we CAN increase overall resin percentage, within the limits of a strain.
And we CAN titrate the side-effects of our meds.

That, gentlemen, is the true power of narrow spectrum growing IMHO.

How's dat for pragmatic, HG?

Aloha Y'all

Weezard

 

[Weezard]

You gonna finish dat sausage?

You gonna finish dat sausage?

Back! (I couldn't help eating one of the sausages that were done before returning)

I'm not gonna bullet point each and every statement because you and I are in complete agreement in this particular respect. I almost wish you hadn't replied so quickly to allow some of the gears turn in other people's heads, but I must say I would have done the very same thing you did by replying quickly.

I was in da neighborhood.

There were quite a few people in the last six months who asked me to help them build a LED system, but yours is the build I've ever seen. Would you consider starting a thread to assist DIY builders?

Have considered.
No can.

How come?
Well.

IC has to make a living.
IC has advertisers.
I've already done an excellent DIY thread on the cdot.
I'm old and cranky.
The industry is catching up to us.
And, Ledengin is out of the 15W. 660nm. leds presently.

Mahalo nui fo' da kudos, brah.

Aloha wit a grin.
Weezard

 

[guest456mpy]

Mr Pragmatic!

Mr Pragmatic!

Weezard, you got me smiling so wide I can hardly contain myself!

You are a true Weezard, no holds barred...

Many thanks on behalf of many who may read

You have spoken truly, plainly yes indeed

many karma to you, but not mine to give

but true karma from those who live...


Feel good? ya finally got me to release my inner poet.

H.G.

Jah bless you weez

 

[Weezard]

A dhammic life is it's own reward.

A dhammic life is it's own reward.

Was aimin' at play, but I hit record.

Mahalo, my poetic friend.

For you?
A haiku.

"Shards of pure color
Grew large buds with magic rays
Tonight, we smoke bliss." -W. Zard

Aloha,
Wee