Discussion of the pragmatic application of LED's

[treefrog]

My past post was large and I was interrupted while writing it, so there was some post inbetween that I didnt see until I finished.

so about fertilization, I would like to add that what treefrog described may be K deff aswell. But probably caused by excess Ca (and probably, Mg) in the media. K is well uptaked when its present, and as formula was the same than worked fine with HPS, the problem must be related to it not being enough in the media.

Can you detail how were temperatures in the LED chamber, treefrog? Did you tracked water consuption? Was it much lower than when growing with HPS? If so, how much? Do you know the nutrient profile you used? Did you used different ECs? I feel tracking these issues is the key to improve our LED grows.

Hey knna, thanks for the info!
I use a soil-less mix, with dolomite limestone added, @ 2 tbs per gallon. There is also azomite in the mix @ 1 tbs per gallon. I don't monitor PH or EC. I don't know what "EC" is anyway. I've always used organic, soil-less, so don't have any experience with anything else.

I also use rainwater, so I made a mix long ago that is 1 part epsom salts and 2 parts ag-lime, which is a high calcium lime. That's my personal "calmag" formula, lol. It works great!
I generally use 1 tsp of that per gallon of rain for all watering. Every now and then I will run into an individual that needs more than that, but typically, it's just right.

The water needs haven't changed any since switching to LED. I think it's because my temps have been the same in either case, about 77f to 80f around the canopy. The difference is the amount of vent fan needed to maintain those temps. All the way on (170 cfm) for HPS, to almost off for LED. I use a speed controller.

Do you guys agree with the often stated ideal LED temp being 85f?
I think I'd have to turn my speed control dial down to... less than one, lol.

It's nice being able to have LED conversations without all the BS.
I think the problem is in comparing them to HID. If I had been using comparisons for marketing purposes, I would have called LED's short, if not equal. That way, if someone gets more bud, they're excited, instead of bitching.. and the good word passeth, lol. LED is a completely different beast, and needs to be addressed as such. It's nice to be able to do so.. Thanks folks!

 

[guest456mpy]

treefrog,
I have been running my grows at 77-78 deg F. Works for me anyway. I'm sure you can go as high as 85 or more, but I'm not persoanlly aware of any advantage.

H.G.

 

[SupraSPL]

A lot of posters mentioned increased potency and aroma. I have noticed this effect even in vegging. I think Weezard's 'piling up' theory is right on.

Thanks KNNA for reinforcing the inverse square law issues and the even light spreading. I agree it is commonly misunderstood and an important advantage of LED.

I have been noticing slight fertilization problems during veg also. Symptoms are interveinal chlorosis and in a few bad cases necrotic spots and brown leaf tips. It affects the leaves that get the most light which explains why I never had these problems when vegging with fluoros. It makes sense that it could be calcium, magnesium or potassium related, especially because I use R/O water. I have been playing with dolomite lime, blackstrap molasses and epsom salts trying to sort out the problem.

It is worth mentioning that I potted up a few cuttings into Epsoma organic potting soil and the problems disappeared despite a low runoff PH 5.5-6. Now I am seeing the healthiest and most vigorous vegging growth I have even seen from MJ, and that was with the LED only on half power ~250mA.

 

[DonkeyPunch]

LED growing clearly reduces transpiration and water uptake, due the reduced temperatures and, more important, the lack of InfraRed. Less water uptake obligue to make some adjustements.

Forgive my ignorance, I fully understand how heat would play a role in water uptake/transpiration, but it is not immediately apparent to me why infrared plays a role. Would you please give me a brief (IE don't waste your time typing up a research paper on it) explanation, or point me in the right direction on that? Also, and again my ignorance on LED comes into play, but as we all know, infrared LED are available. I am sure there is a very good reason they are not being used to help combat this problem, yet I am ignorant as to what it is.

I realize this thread is not geared towards my questions, and I apologize for cluttering this thread with it. My intention is not to clutter the thread and if any of you would prefer to answer in PM to keep the thread clear of my stupidity, I would completly understand.

 

[knna]

Forgive my ignorance, I fully understand how heat would play a role in water uptake/transpiration, but it is not immediately apparent to me why infrared plays a role. Would you please give me a brief (IE don't waste your time typing up a research paper on it) explanation, or point me in the right direction on that? Also, and again my ignorance on LED comes into play, but as we all know, infrared LED are available. I am sure there is a very good reason they are not being used to help combat this problem, yet I am ignorant as to what it is.

I realize this thread is not geared towards my questions, and I apologize for cluttering this thread with it. My intention is not to clutter the thread and if any of you would prefer to answer in PM to keep the thread clear of my stupidity, I would completly understand.

Dont apologize, bro, its a very good question and fully on topic.

Water has huge absorbance on some IR peaks (if you look at a graph of sunlight, you quickly see the valleys produced by vapor water absorbance in atmosphere), with the effect of raising its temperature. IR is called radiant heat. While temp aroud the leaves obviously affect it, heat transfer is a slow process, however IR heats instantaneously water inside the leaves.

All light sources except LEDs emits IR in large amounts, thus we get used to grow in the presence of it. Nature is used to it too. But IR is not used for photosynthesis (because wavelenght is so long that photons dont carry enough energy to drive it) and dont have noticiable biological effects neither. Thus its perfectly posible to grow plants without it, but it affect water temperature into leaves and we must manage to overcome it. The gap between actual water temp and evaporation temp determines the energy plants need to use to transpire (within many other factors, but its one more).

In general, the lack of IR is an advantage. Without photosynthetic effect and minimal (if any) overall biologic effect dont make much sense to waste energy and money on it if we can overcome possible problems created by other ways. On the other hand, lack of IR does way easier to cool down a given space.

If a grower want to have IR in the grow room, I believe using too a HID is the way to go.

 

[tSoG]

awesome thread. I need to practice my soldering, before I try building an array, but my question is this, what is the source for these top shelf LEDs? Also, this may be silly but why the "bigger is better" push for 1-3w LEDs, are the smaller samples unable to put out as much light per w?

 

[joe4444]

awesome thread. I need to practice my soldering, before I try building an array, but my question is this, what is the source for these top shelf LEDs? Also, this may be silly but why the "bigger is better" push for 1-3w LEDs, are the smaller samples unable to put out as much light per w?

My understanding is that it's similar to low watt HIDs v. high watt HIDs. Lots of people grow prime quality buds with a 150W HPS that rival what the big boys do with 4-6X the power. Those people get the best results by training (e.g. SCROG) to keep the buds as close to the light as possible. Growing 5ft plants with quality buds from top to bottom under a 150W HPS is almost impossible. In other words, LED lamps using 1W diodes are optimally effective only within (I'm guessing here) 12in whereas 5W diodes are effective at greater distances.

I think there are other advantages, too, but I'm still new to these lights.

 

[Tyrone420]

Does anyone have any experience using LED street lights??

I believe you can find them in a variety of temperatures.

 

[guest456mpy]

Sorry, Tyrone.
This thread is for the application of LED's as a technology. It was really not intended to discuss one brand vs another. I hope you understand.

Thanks!

H.P.

 

[Tyrone420]

Wow, no I don't really understand why my post got erased because that looks like some high tech shit, and I don't see a single thread on here about it? ..regardless of what brand. That is just a spot light, made somewhere in China. It's not some LED plant light company.

 

[Tyrone420]

Please explain to me how this is not related to LEDs as a technology -
A 100watt emitter with a heat sink strapped to it? That seems like it has "Technology" written all over it to me.

 

[TrichyTrichy]

Heya Hempy

 

[guest456mpy]

Tyrone,
I am not a Mod, nor do I ask for any posts to be binned.
I only try to help where I can. I hope you understand.
H.G.

 

[FreezerBoy]

TOU Article 8

 

[guest456mpy]

Thanks to Trichy and Freezer Boy to tending my thread in my absence.

I have spent many hours lately meditating, and time slipped away from me in this "dream" we all call reality.

Tyrone,
Pragmatism requires that all things be tested by experience so I cannot answer definitively. I will comment that there are no "real" white LED's. In order to make light emitted from an LED white, an emitter is encased in a phosphor coated outer shell, when the photons strike the phosphor coating white light is thereby emitted. This would suggest that "white" LED's are inherently less efficient than single band emitters.

All the posters thus far have used multiple choices of single banded emitters that are close to well known plant behavior points. I will not enumerate them since they are already discussed at least cursively elsewhere in this thread. If you have a curious mind disposed to actions, why don't you be the first to try these products and document your grow as to add to the body of knowledge already gathered?

Thanks for your input and understanding,
H.G.

 

[blimblom]

wow thats a really nice no flame, no spamming by commercials, no big egos to go around.
Thanks hempguy, and of course thanks for all the contributors.

As I understand getting 25-29 deg C on your plants is the optimal range.
All those years we are fighting excessive heat by HPS or flouros, etc
its the first time we have to sometimes fight excessive cold.
I have an in house grow closet so, if its too cold, I turn up the room heat a little bit more.

But dont we have just to reduce the flow of air accordingly? Keeping a light negative draw is mostly ok for controlling smells and recycling the air inside the closet (tried it with perfume in the closet) . Its also ok for letting the leds add some heat, or using additional CO2 as some have suggested.

For my grow, low noise, low heat is always a plus, so in that part LEDs are an optimal choice.

So as KNNA has said, we have to adapt to new growing patterns.

And as we try more and more grows and more and more strains, things (LED wise) will improve (even with the same bins)

PS while I hugely enjoy the conversation, I think that we sometimes tend to over-engineer . I understand that most of us are 60% nerds / 40% growers, and over-engineering is our fetish, but I think that experimenting over a wide variety of new conditions is more beneficial than the angle of the lenses, or the quality of the mylar
having said that, please do continue, as I said, I hugely enjoyed it.

 

[guest456mpy]

But dont we have just to reduce the flow of air accordingly? Keeping a light negative draw is mostly ok for controlling smells and recycling the air inside the closet (tried it with perfume in the closet) . Its also ok for letting the leds add some heat, or using additional CO2 as some have suggested.

I have also been successful in controlling temperatures by controlling the flow of air, it works quite well even with 500 watts of power. I use a carbon filter, not perfume.

So as KNNA has said, we have to adapt to new growing patterns.

That is what I meant to imply in the title of the thread!

Thank you for your most thoughtful additions to the thread!

H.G.

 

[VerdantGreen]

very interesting thread, i need to come back and read it again (i dont go too deep into the tech side im afraid). ive grown quite a bit under LED's this last year or so and found it very successful, especially when the cabinet has been designed specifically for the LED unit. i grew decent buds at around 30w/square foot.
recently i had a unit 'custom' made (90degree lenses and some green spectrum added) and for the firs grow used it in quite a small cab - i found that at 50-60w/square foot i am getting buds of the size i used to get under my hps at a similar watts/square foot.

next i will try 40w/square foot and see if i can keep that same bud development.

one thing i did when designing my new LED cab was to put the air intake at the top and the exhaust at the bottom to better suit the cooling fans in the led unit (so they arent fighting the exhaust) and also to 'harvest' some of the heat from the unit to warm the cabinet. seems to be working well.

cheers

VG

 

[guest456mpy]

Thank you, Verdant Green.

Although counter intuitive I have found that there are cases where having air flow in this way can help bring temperatures to where the plants thrive. There is little to no radiant heat presented to the plants when using LED's so we must adapt out usual growing methods. We must carefully analyze our grows at this point since there are no established guide lines yet. We must all listen to what our plants are telling us and act accordingly!

This gem is just one of the many ways we can fine tune our grows in order to reap the results LED's suggest. Thank you very much for your valuable addition to the pragmatic approach.

Be Joyful and Live!
H.G.

 

[one Q]

hempy, knna, & weez help my out right quick

How tight of a beam do you guys use on your LEDs? I was looking at ledgrow.se and seeing that they use 120* 3w lights. Im I thinking right that smaller watt diodes need a tighter beam to get similar results as higher watt diodes?

So a 1w (HG) at 60* is similar to a 3w (LG) at 120* ??? But then I think that the 1w/90 would still not get as good a coverage... only directly under the diode. hmmm.

Ideally, trying to cram as many LED watts as one can in a set space, but what is the "ideal" amount? Do we still do 50w/sqft? Is there a better calculation for this new light?

Sorry I dont have much to add to the discussion, but i WANT to be able to in the future.

Quality.