LED Lab 2009

[LeoRexTyrannus]

If it isn't photons than the current logic doesn't make sense. by PAR and PUR it should be excelling, not falling behind, it lacks photons that's the only difference.

Yeah I give up on the science of it, because if it isn't the above then who cares it doesn't make scientific sense.

 

[Oldmac]

May I add that this may be evidence of why the TI SmartLamps and SmartBars can't match an equivalent HID in biomass.

What is this statement based on? My experiments show something else completely. I used 2-TI ProBlooms together (660w total) side by side with 1kw HPS (1150w total) each set up covering a 4'x4' area and the finished bud weight was very equal, with the LEDs using 490watts less!

 

[Oldmac]

Sorry, old feeble mind....I meant to post a couple of pictures of my side by side experiments.
Here they are, 2 TIs vs. 1kw HPS. (well 2 actually, but each is doing 4'x4')

 

[billyjojimbob11]

Hans has a conclusion from the NL's...

http://www.ledgrow.eu/ft.html

Anyones thoughts....

 

[knna]

If it isn't photons than the current logic doesn't make sense. by PAR and PUR it should be excelling, not falling behind, it lacks photons that's the only difference.

Yeah I give up on the science of it, because if it isn't the above then who cares it doesn't make scientific sense.

Hey, Leo, dont give up!

Just you may not expect than general guidelines may explain all that happen with very complex living organism as plants.

All is related and for a plant, how it grows depends of all enviromental conditions (light density, light quality, temperatures, humidity, nutes, substrate composition...) and its own genetic. And all work together and at same time.

We usually try to increase our comprension of what happen on complex systems by studing separatelly each factor affecting them. But still with a good knowledge of the response of individual factors, putting them all together is a real challenge. And still if we can do it very, very well, often a system is more than the sum of its parts.

But yes, the baseline to study plant's reaction to light is definitively photons (uE). But in order to be able to say how much or how good a given spectra works with MJ, we need more knowledge of what we actually have.

Althout there is a direct correspondence between uE and yield, this correspondence is mediated by a coefficient tipical of each different spectrum. And we still dont know a clue od what determines if this coefficient (the efficacy of the spectrum) is higher or lower. We have a initial starting point with the photosynthetic curves to isolated wavelenghts (McCree or Inada), but we still need to determine the response at different irradiance levels, interaction at different CO2 levels and find the sinergies between different wavebands and the margins where they work.

So, we have some facts as starting point, but we are very far to be able to say, just using the uE amount, what yield it may produce depending of spectrum composition. Thats why we need to experiment and see what plants says us about it.

I believe that the best attitude when leading with plants is humbleness. We like to feel as small gods when growing them, pretending that, as we control their environment, we control them. But growing experience teach us that plants are very complex and that we dont understant many of their reactions, so pretend to accurately "controlling" them is just an illusion.

 

[knna]

Oldmac, thank you for thos pics.

But I would like to see figures, not only your opinion (of course, its apreciated). Grower opinion is important, he is who see how plants grows day by day, but figures are esential to put grower opinion into perspective. And as has been noted, standarized figures would allow us to compare, with all the limitations due each setup and grower skills are different.

From the pics, I would say that its difficult to extract conclusion of the perfomance of those TI Smart lamps due plant below them arent isolated from the light coming from the HPSs (the second pic shows it, by showing the footprint of the HPS on the wall). Im not saying you to put a light barrier between them, I know it would be stupid yield wise to waste the light coming from the HPS, but it does difficult to extract conclusion about the perfomance of the TI lamps alone.

Seeing the setup, I have a question. Does plants under the TI Smatlamps finish the flowering under them, or its a perpetual setup where plants starts under them and finish under the HPSs?

Please, Oldmac, more details of the setup, it seem kick ass!

 

[knna]

Hans has a conclusion from the NL's...

http://www.ledgrow.eu/ft.html

Anyones thoughts....

I pretty much agree with them. But some statements need to be some more deeper:

1# LEDs are more efficient than HPS. Is not true!

LEDs are currently less efficient than HPS, especially the blue ones and they are many times more expensive. A typical HPS gives about 140 Lumen/Watt, where the best LEDs still are at 100 Lumen/Watt. The often-heard statement that LEDs produce less heat than normal assimilation lighting is a misconception. Because the energy conversion is worse than in HPS, the heat per watt still higher than that of HPS. It begins to approach each other but just for the red LEDs and white LEDs. The heat is better to handle because it does not come out the front as radiation, but is concentrated on the back of the chip and can be lead to proper heatsinks.


Main statement is true. Currently, LEDs are less efficient than HPSs. Or at least, most of them.

Using lm is no sense when comparing light for plants, and may be very misleading.

But it depends largely of the LEDs being considered, and on what units we do the comparision. While HPS's efficiency is pretty constant, LEDs efficiency strongly vary between models, bins of same models and current level used.

So most LEDs used have lower efficiencies than HPSs, especially those being using on all comercial grow lamps (today). But there is currently LEDs avalaible than are more efficients than HPSs.

For example, the group 15 of Royal Blue LEDs of the Cree XR-E is achieving about 39% of energy efficiency (PAR Watts delivered/Watts burned) when working at 350mA (1,08W). Its over the efficiency of any HPS in the market. And group 16, about 20% more efficient than 15, has been announced and probably will be avalaible before this year ends.

On the other hand, if instead of the pure energy efficiency, we consider the quantum efficiency, still the HPSs are over that LED, because it just hold 3.69 uE on each PAR W, while HPS tipically holds 4.8uE/PAR W.

But the comparision would depend too of if we compare with a unreflectorized HPS, or with a reflectorized one. A reflector tipically absorbs about 25% of the light emitted, 35% for a glass sealed one. So if we compare the efficiency of that blue LED with a reflectorized HPS, it still gains, both on PAR W or uE for each watt burned.

On the red side, LEDs are improving more slowly and still are below HPSs. But if we compare quantum efficiency of a reflectorized HPS, there are red LEDs that surpasses them. Not a unreflectorized, but yes for a reflectorized.

Any other LED color is way below the efficiency of HPSs. White ones are improving very fast and best ones are currently reaching the level of reflectorized HPS. Its expected they reach the level of unreflectorized ones in 2 years (and current development is going faster than expected, so its possible it happen earlier).

So for reflectorized HPS setups, its possible to use LEDs with higher efficiency than HPS, for blue and red LEDs. But anyway, currently we need to use the better LEDs and bins of the market to be able to equal or surpass by little HPS's efficiency. Any other LED is below HPSs, and many times for a large margin.

Important note: All these has been refered to the most efficient HPS, 600 and 1000w. At lower wattages, they are less efficient, near half when dropping to 70w models. When comparing with HPS wattages of 150w or below, good LEDs are clearly more efficients, and by a large margin.

2-LEDs are more efficient because more light at the most efficient parts of the spectrum is used. Is not true!

All photons in the visible light are used at almost the same efficiency. There is a slight decrease for the green photons, but it is no way as bad as Led-panel salesmen would like you to believe. (For fun you can compare this official graph with the ones found on Led-panel sites)


Fully agree. That marketing hype is fully off base.

But that not dismiss the possibility of achieving spectrums with way better efficacies, by exploring and using positive sinergies between wavebands and adapting spectrums to each plant specie likings. But of course, it dont have anything to do with the fake argument of "HPSs waste 90% of the light".

3# LEDs have to be placed within a few cm of the plants. Is not true!

Light does not lose noticable strengh while travelling, but you have to make sure it is focused properly. Most LEDs have an angle of 120 degrees, you can use lenses or reflectors to make a more narrow beam. Lenses create lightlosses of at least 15%, reflectors only effect the light that is send to the sides and are therefore better.
Some people think LED-light has less "penetrating power", which would be another reason to put the LEDs as closely as possible to the plants. Light = light, the penetrating power of a Red photon produced by HPS will be the same as that produced by a LED.

Agreed. Very good observations. I think Ive written a lot about this topic in this thread.

LED Facts

* The light efficiency produced by a LED depends highly on the working temparature, keep the temperature as low as possible by using adequate heatsinks.
* The light efficiency produced by a LED depends highly on the current, using the LEDs at maximum current can reduce the efficiency dramatically, this depends on the model of the LED.
* LEDs have an exceptionally long life (40,000 hours) and they are very resistant to bumps and vibrations. Both life and light output are negatively affected by higher temperature.
* LEDs are available with different emission spectra, which make it possible for processes to send light of different wavelengths. You can control the shape of the plants by using different mixtures of Red/Far-Red and Blue, for both the vegetative and flowering stage. See the document about Light Color below.
* With LEDs it is easy to control the light and get it where you want it.
* LEDs are safe since they contain no glass and operate at a low voltage.
* The intensity of LEDs can easily be controlled with dimmers.
* LEDs are small and manageable, this enables them to be placed in rows at the bottom or sides of the plants, or to create 2 rooms on top of each other.
* LEDs radiate almost no heat to the front, therfore the distance from the plant may be very short.
* The impact to the environment outside the greenhouse can be significantly reduced, which is an important environmental aspect.

It sums LEDs advantages pretty well.

I only would explain a little more about LED's duration. Its strongly affected by working temperature. It we define its useful life as the time to light emission takes to fall bellow 80% of the initial emission, most LEDs on the market working between operating specs but without a very good thermal setup last about 25000h.

But if running very hard or hot without good cooling, many of them dont surpass 10000h, and may be burn in less of 1000h with a bad setup. On the other hand, with a very good cooling or working at currents below the nominal, they may last up to 60Kh before losing 20% of the initial light.

About LED duration, LED model is too esential, and the larger difference between main LED brands and the rest. Fortunatelly, at the LED improvement rate and droping price/perfomance, many people is going to replace their LED lamps before the end of the useful life.

 

[billyjojimbob11]

Thanks

 

[LeoRexTyrannus]

Sorry if I seemed rude, didn't mean to be, and look from what I just read basically even if we have environmental controls, know the par and pur, and the ue of the device, and we keep it at a constant temperature to maintain light purity, then there is still this X factor of the light intensity that was just eluded to, so perhaps the biomass trigger is in the yellow and it's the intensity applied that is the key, or perhaps it's the far red after all and it's the proper intensity of it.

Basically this means a lot more experimentation is needed to know anything definitive and since strains have their own unique characteristics concrete is ALONG WAY OFF.

Since this is the fact of the matter, we should go with what we know in any productive endeavor and then experiment on the side. Seems like small chamber grows are called for.

I wasn't meaning to offend any SmartLamp/Bar owners, I know I've seen several several threads on the internet talking about it not yielding properly, of course those could be tainted by them not properly cooling their reservoirs. I digress this isn't about Theroem or anything to do with them. I kind of don't like those guys because they claim to make their own LEDs.... and that's just BS. Maybe they have someone fabricate them for them.. but make them themselves? Off topic but odd none the less.

Thank you Knna for being very fourth coming for any potential adapters. I'm sure they'll prize your clear and honest message of HID being superior right now. And HPS vs MH vs CMH, I take CMH I've seen the resin on HPS buds, it's anything near as dense as the CMH, but the CMH produces less biomass from what I've seen. It's merely a choice of quality vs quantity, both are valid, neither are wrong.

I think you're all doing fine work and I'd never discourage anyone unless I thought there was honestly something better. I appreciate all your grows, especially the ones with those tasty bud porn pics.

Knna since we can control LED spectrum by its temperature can't that be used intentionally to experiment? I believe you're right as well that White LED will be the one they push the hardest, and since it's full spectrum much of the experimentation might be made null by the fact they would be available from mass production at such a low price by comparison to eliminate the need to experiment.

 

[Oldmac]

Oldmac, thank you for thos pics.

But I would like to see figures, not only your opinion (of course, its apreciated). Grower opinion is important, he is who see how plants grows day by day, but figures are esential to put grower opinion into perspective. And as has been noted, standarized figures would allow us to compare, with all the limitations due each setup and grower skills are different.

From the pics, I would say that its difficult to extract conclusion of the perfomance of those TI Smart lamps due plant below them arent isolated from the light coming from the HPSs (the second pic shows it, by showing the footprint of the HPS on the wall). Im not saying you to put a light barrier between them, I know it would be stupid yield wise to waste the light coming from the HPS, but it does difficult to extract conclusion about the perfomance of the TI lamps alone.

Seeing the setup, I have a question. Does plants under the TI Smatlamps finish the flowering under them, or its a perpetual setup where plants starts under them and finish under the HPSs?

Please, Oldmac, more details of the setup, it seem kick ass!

Hey knna,

Those are pics of a grow I'm partnered in. And those where taken at least 10 months ago, and your obsevations are right on, they where starting 12/12 under the LEDs, then moved to the right under HPS. We had 3 stages of growth. My partner was a "LEDs don't work" guy and it took awhile for him to trust me enough to run start to finish under LED. hehe

6 months later, we ran start to finish under the TI LEDs, with excellent results and he started to come around. While there is no barrier between LED and HPS it is interesting to note that the first row of plants on the HPS side grow TOWARDS the LEDs. A couple of months ago I took the 2 TIs (660w) and added a 4-4' T5 vho frame (340w) to it for 1000watt total hybred light....and now there is NO comparison to the 1kw HPS.

Recently we had to shut down 1 HPS (in corner) because of temperture issues. So now there is distance between the competeing light sources.
My partner just said to me last week, "what we really need is 6 more of those TI ProBlooms"....what a difference seeing them actually work, without the heat bs, makes to non-believers.

couple of pics of hybred light, I have more pics in an album. (I'll share some data, later when I have a little more time)

 

[knna]

Thanks for clearing it up, Oldmac. I understand it much better now (waiting for figures, when you have time).

While there is no barrier between LED and HPS it is interesting to note that the first row of plants on the HPS side grow TOWARDS the LEDs.

Well, I dont believe its surprising. Phototropism is mostly signaled by blue light, and compensate blue signaling with a red shifted spectrum requires was higher intensity.

Ive suggested many people with vertical setups to add a powerfull blue led over each plant, so the plant dont go toward the side HID, but towards the upper blue. 450nm is the peak of phototropism action spectrum.

A couple of months ago I took the 2 TIs (660w) and added a 4-4' T5 vho frame (340w) to it for 1000watt total hybred light....and now there is NO comparison to the 1kw HPS.

Wouldnt be a 4-4' T5 frame 240w? 54w each tube + ballast losses. It sum 900w instead of 1000w.

Taking into account that the TIs have way lower energy efficiency than the HPS, and that T5 have similar, or just slightly lower efficiency, it means that the LED+T5 setup is delivering to plants aprox 50-60% of the uE of the HPS.. So if its overyielding it, it means the LED+T5 setup is achieving double the spectral efficacy, that is exactly what we are looking for. Using same spectrum but with similar energy efficiency than HPSs, we could achieve double g/w than HPSs without problems.

That 100% enhancement of the spectral efficacy is higher than we are getting on the spanish forum test, where its being over 50% of enhancement respect to HPSs (compared to results of same growers using same strains), but not reaching double efficacy. I would like to have some figures of that room, so we may calculate it more accurately.

Anyway, that enhancement is way higher than could be expected by extrapolating McCree or Inada curves, showing that sinergies due to the use of the correct wavebands have the potential of strongly increase productivity of light . Potential gain for findind optimal spectrum may double the spectral efficacy, so we are working to get not merely 25-30% enhancements, but over 100%.

This promise a brilliant future for LED growing.

what a difference seeing them actually work, without the heat bs, makes to non-believers.

Most people want see to believe. I think its right, and the marketing hype about LED growing compared with many deceiving journals has done many skeptics.

But now there are many people who has learned to differenciate between marketing bs and what LEDs are capable of doing actually, well used and installing enough light. As people starts to see sucessfull LED grows, they will move to LEDs, as prices does it worthy for each one.

MrX grow is being wonderfull too. With outdoor temp on the 100F range, he is not using AC and getting this, with two 120W panels:

On a side note, have you thought about slightly turn T5's reflectors pointing towards the center of the grow (below the TIs), in order to get a better mix of the light?

 

[knna]

Knna since we can control LED spectrum by its temperature can't that be used intentionally to experiment? I believe you're right as well that White LED will be the one they push the hardest, and since it's full spectrum much of the experimentation might be made null by the fact they would be available from mass production at such a low price by comparison to eliminate the need to experiment.

Spectrum shift due to temperature is too small to work on it on purpose. When I work with spectrum optimization, I think on wavebands instead of wavelenghts. Amount of experimentation needed to fine tune to exact wavelenghts is excessive, I would be happy finding what wavebands and on what percentages have the best spectral efficacy. Once done, it would be the time for fine tuning and use temperature shift, but I believe that only provide marginal benefits, compared to the envisioned strong enhancement if we are able to find the right wavebands combination.

Still if in the future, white LED may be used to growing sucessfully, it welll worth the job of finding the optimal spectrums.

Technology limits the energy efficiency of any lighting device.

But if we can find the optimal spectrums, those that produce more for a given amount of photons, we will be able to select in each moment the best lighting devices able to give it with the best energy efficiency.

As the energy efficiency of the lighting devices increases, for example of LEDs, we are going to be able to keep increasing the productivity of our grows at the same rate.

But, whatever the light used and its energy efficiency, if we find the optimal spectrums we are going to give a huge jump ahead on productivity.

Until now, lighting technology didnt allows us to experiment with different wavebands mixes. But now we can do it with LEDs, so its a must to use this new technology to find the optimal spectrums for growing MJ indoor. This wont benefit LED growing, but growing with any type of current or future lighting technology.

Thats why I split the optimal spectrum research, that concentrates only on the spectrum efficacy, from the mere growing with LEDs, where the target is to produce as much as posible with what is currently avalaible, and that may change in little years.

Im really not concerned at all for the energy efficiency of research setups. I dont mind if I get 0.2 or 1.2 g for a given amount of watts burned. Im interested on knowing the spectral efficacy, g/uE of each setup.

I dont need at all that the grower says how many watts he is using. But I need to know how much uE he is using.

One good thing about the TIs is they are the only comercial LED lamp that says how many uE it delivers (183 per second). So its easy with them to obtain its spectral efficacy. Just if it was current adjustable by separate color channels, it would be perfect for research.

 

[knna]

Just to clarify my viewpoint a little more:

Yield may be expressed as the product of uE used by its spectral efficacy:

Y=PPF*φ

Y=yield

PPF=photon flux density, in uE, or just E (mol of photons)

φ=spectral efficacy of a given spectrum (at a given average irradiance?).

PPF for each watt burned only depends of the energy efficiency of the lighting device. We cant do anything about it, we depend of what lighting manufactures does avalaible to us.

But we can choose to use spectrums with the highest φ. The problem is we still dont know it for cannabis. But once found, all MJ growers will benefit of this knowledge, whatever the light technology they use.

 

[knna]

smokinshogun, I agree with all you wrote in your last post, but it dont discourage me. I know that still with that limitations, we can find the best spectrums.

The reason? My confidence holds in the large numbers. Stadistical analisis offer great info digging into apparently heterogenous info.

If we get standarized ways to report the esential figures we want to analyze, we can get relevant correlations. In our case, between the spectrum used and its spectral efficacy (yield/uE).

The pioneer study about this topic was performed in the Cannastats project. Respect to lighting, unfortunatelly they hadent the tools required to convert to uE and study results based on it, instead of W/sq ft or lm, but as for the lights used for that time, there was a significant correlation between W/sq ft and uE/sq ft, results are enough meanglifull.

Once thing that must be noted from Cannastats result over a sample of 140-160 grow reports (wish they had been way more!) is that variations on yield due to many of the factors analized werent significant. Yep, there are many factors that affect a given grow productivity, but when you analyze it stadistically, they are not significant, they often compensate between them and those small variations dont affect the positive correlation found for significant parameters.

The four parameters that cannastast found to be significant affecting yield were (99% confidence):

-Lumens (31%)

-HPS spectrum (14%)

-Experience (5%)

-Hydroponic medium (3%).

For that time, only fluorescent, mercury vapor, MH and HPS were avalaible. All broad spectrum lamps, so the study offered little info about spectrum efficacy. But worth to point up that 45% off 53% of positive enhancement of yield was due to lighting parameters, that showed to be by large the parameter affecting the most indoor yields.

So its really possible to study stadistically reports for very different setups and analyze correlation between spectrum and light density used with yield.

But on one thing I fully agree with you, smokinshogun.At the end, we are behind resin production, more than bud production itself. But standarizing a way of measuring resin production is very difficult, IMO. And ideally, if we want to be rigorous, we should have cannabinoid profile info in order to study if light quality affects it and if so, in which way.

But those are requeriments very difficult to achieve. So I prefer to concentrate on what we actually may do, study the correlation between bud production and light used, and hope we can develop a way to study the correlation bud with resin production, and light quality to bud quality. I suspect that the experiments required to study it are going to need advanced equipment (gas chromatography, although maybe relatively cheap thin film chromatography works enough), and controlled studies.

But relation between bud production and resin production, although affected by environmental conditions, is strongly determined by plant's genetic and phenotypic expression. So I think that concentrating on bud production will offer very good and useful info. Its only going to be perfect if we can couple it with studies on resin production and composition, but hopefully, it will come in the future.

 

[LeoRexTyrannus]

Knna my friend, it isn't often in this environment I feel I can make a worthwhile suggestion, but this is one issue I think I can definitely help with.

Simply take a measured sample from each test crop, use bubble bags and condense into hash, the hash can then be definitively weighed, and since the hash is in all reality the thc trichomes and glandular stalks you should have a very accurate method of measuring thc content.

On an unrelated note, you guys are so technical I just have to ask this, please forgive me, I slapped together my ultrasonic fogging cloner, and the timer I'm using now allows me a resolution of 15 minutes, so I have it coming on the first 15 minutes of every hour, on the hour all day right now. My question then is does anyone know of a high resolution timer that isn't insanely expensive? I know a cyclestat would do the job but for the price of the project I just can't justify that kind of purchase for this task. Ideally I'd want something that is capable of 1 minute on, 4 minutes off as all the threads I noted having great success seem to be running that aggressive cycle. Thank you in advance.

And to OldMac, if you're out yielding HPS with a combo CFL+LED grow then fantastic, I think hybrid grows are the perfect way to augment LED weaknesses currently. I'm glad for your success.

 

[billyjojimbob11]

Would love to try Co2 with leds, I will add that to the list.

 

[Oldmac]

knna, The T5s are being driven to vho levels so each bulb is 85 watts for a total of 340w.
I'm using a IceCap ballast to do the dirty deed. I'll try to remember to jot down some numbers tonight when I'm at the grow. Keep in mind I have not done any "total biomass" weights, just dry manicured bud weight. While I've seen the scientific discussion, and realize for the most accurate extrapolation of photon energy to biomass it would give; I just throw stalks, branches and extra leaves away. I'm only interested in da bud.

 

[Weezard]

sadditude

sadditude

"especially when your trying to make HID lights look like crap with numbers. "



"Did that make any sense"

No, not to me.

How 'bout you Knna?
Sure don't sound like your motives either.
<sigh> that's just, sad.

Weezard

 

[knna]

and especially when your trying to make HID lights look like crap with numbers.

Sorry, I know my english is not good, but im having a hard time trying to imagine from where you took that impression.

Am I trying to make HID lights like crap? I think its more the opposite, but maybe you are reading a different thing that Im trying to write.

I try to analyze the advantages and disadvantages of each type of light, with a free mind. I tend to advice to use the type of lighting that adpts the best to the style of growing and the caracteristics of each grow. I advice very often to use HIDs to the people. Some people ask me for a LED lamp to replace a large room with HIDs and I tell them to keep with them for a while, that currently it isnt cost effective.

Im always pointing out the bs about the HID "wasting power" and such statements, and I say that HIDs works pretty well and that we really need to do it very well with LEDs to be able to overyield them at ther current stage of LED's development.

So please, explain me why do you think Im trying to make HIDs appear like crap.

In the end, it really comes down to how much power (kwh) it took to get this certain amount of amazing bud (g) and not just how well the light is at turning each 'insant?' watt into grams.

Yes, of course that any study must be based on the total amount of light. Specifically, with the amount of photons used along the grow. Mols of photons is the unit often used for this task. You can see as botanist suggest optimal amount of mole of photons for each crop. Then it must be splited into the photoperiod used.

But the instant amount of photons, emitted per second, is too a meangliful figure. Its the same as reporting results based on the watts of HID installed. Its just a orientative figure, because its not the same a grower using a 1000W HPS on a 10/14 photoperiod than on a 12/12 or 14/10. Any serios study must take into account the amount of KWh used along the grow, but the average "instant" unit is useful to know aprox the light density used.

Using uE/second or mols of photons (a mol is one million micromols) along the grow is the exact correspondence to Watt installed and KWh burned along the grow. Exactly the same.

If I prefer to use uE instead of watts burned is because although they are related across the energy efficiency of the lamp, working with uE let us concentrate on the spectrum efficacy. KWh interest to people just wanting to grow pot. Mols of photons interest to those interested in research. Its what Ive tried to explain on my last post, but it seems that unsucessfully.

We can do anything about the energy efficiency of the lighting devices we use, but we can do a lot to use the mix of light that get the best results.

 

[knna]

knna, The T5s are being driven to vho levels so each bulb is 85 watts for a total of 340w.
I'm using a IceCap ballast to do the dirty deed. I'll try to remember to jot down some numbers tonight when I'm at the grow. Keep in mind I have not done any "total biomass" weights, just dry manicured bud weight. While I've seen the scientific discussion, and realize for the most accurate extrapolation of photon energy to biomass it would give; I just throw stalks, branches and extra leaves away. I'm only interested in da bud.

Oh, thanks for clearing it up.

I think we have talked about this before, but I dont like overdriving, for the reduced life that results from doing it.

But when doing it, I think is a must to use T8 tubes, as they are cheap and have margin on the working specs to do it.

But T5s are different. HO T5s are in fact overdriven HE T5 (check how both types of T5s have the exact relation of overdriven fluos: near 2X the power for a given lenght with 70% more output). The only difference is T5 are adapted to work at higher temperatures without the fast degradation (of overdriving a HE).

T5s are expensive tubes designed to loss about 10% of the initial lm along is entire life of about 20Kh, 20% on worst scenario when working into specs. I think is a waste to have to replace them after less than 2Kh. But, if you dont have problem with it, its your choice. Just I felt I should comment it.

Due the T5 HO is already overdriven, Im not sure that overdriving them results on a light output increase at the same rate than when overdriving a normal one. Have you checked with a luxometer the actual gain?

I understand you about only weighting the buds. I do the same. But in this early stage of LED growing development, spending 10 minutes on weighting the waste product will help us a lot to learn. We just need that a group of LED growers agreed to join taking for a while the relevant data for each crop in a standarized way.

We are now just talking about how it should be. If we decide to go along, we should open a new thread, put in clear what data to recolect and start doing it. Im thinking to do it on a own web, so any LED grower interested on researching may colaborate. Maybe it would worthy to make two files, one for people wanting to spend its time recolecting all the required info, and other for general LED growers, that if many of them give reports, still when unstandarized and incomplete, should throw light on the topic.