New high powered LEDs

[Luke Skywalker]

There's a HPS vs LED shoot out thread here on the AN forums... HPS vs LED shootout

 

Guy doing it will be producing them for commercial sale in the near future... looks great to me...

 

It's early days really, but yeah, we'll see. At the moment, $ are a factor, but if you can get around that....

 

And SS, I don't know where you heard about the heat=resin thing, but I'm not entirely sure you're correct. Heat and all other things being ramped up in sync may produce higher yeilds, and perhaps allow maximum expression of the genetic potential, but it doesn't necessarily follow that to get the most resin on your plants you should increase temperature.... I think I actually recently read something that said the opposite.

 

Got any info that you can point to about that SS?

 

Afghanistan/Western China can be pretty cold @ altitude....

[freddie]

Great link there Luke (although that gopher bouncing around started making me dizzy). This gets more and more interesting, especially the suggestion that LEDs may increase potency.

 

Not sure about the heat and potency? Cannabis grows in such diverse climates.

[Al B. Fuct]

Interesting post, but you're a bit off about luminous intensity. To think about it intuitively: You put two light sources together and you double the rate at which photons are emitting. If the light sources are shining in the same spot, you'll double the amount of photons hitting that spot. So if your meter is in that spot, twice as many photons will be hitting it. You can verify this yourself with a lux meter. So if our base light source isn't strong enough we simply add more to produce more photons, which are the base particles that provide energy for photosynthesis.

 

Luminous intensity from multiple sources acts more like voltages in parallel. If you put two 1.5V batteries in parallel, you get 1.5V. Same with luminous intensity. If you put two 1500 lumen lamps next to one another, you have 1500 lumens. Neither lamp gets brighter. Intensity is analogous to voltage in that it is a measure of the 'push' or energy level behind the photon. Lumens are not a measure of the quantity of photons, rather the total energy pushing them which the human eye perceives as brightness.

 

It just so happens that I have a lux meter. I set up two 20W CFLs in two fixtures, let them warm up for about 5 mins and measured the luminous output around them at a distance of 50mm.

 

 

The lux meter read around 65-70K lux from the sides of either CFL. When the lux meter sensor is placed so that it is within as close to 50mm as practical to both tubes, it still reads 65-70K lux.

 

Neither lamp got brighter- there's just more photons being banged around. Remember, we're not measuring the quantity of photons but the energy behind them. That energy, or intensity, is what drives the mechanism of photosynthesis, not the quantity of photons. I could put 1000 20W CFLs in a room but it still won't grow the same amount nor density of buds for me as a 1000W HPS.

 

Simple as this- lumen figures from multiple light sources added together are meaningless. The amount of luminous intensity is no higher than the brightest light source.

[Pam]

Well I'm going to find out soon enough. The new box with the leds is almost ready, all lined in shiny silver mylar. Now I know that I HAVE seen an led grow light with a light meter that was putting out I think 158? Regardless, the 12" red traffic light throws BRIGHT blinding light for at least a meters distance. Police are using LED in their lights as well, and we all know how blinding they are.

 

The point is made by the sellers of led grow lights that lumens are a measurement of how the human eye sees light...not plants. and that 98% of the light put out by red and blue led's is used by the plant, as opposed to a much smaller percentage with HID lights. Therefore, because the plants can make use of more, they actually need less...

My experience with just adding blue to the veg chamber is that the plants seek out the blue light ignoring the abundance of other light, in my case 4, 120w cfl floods. And I only have one pishy little blue LED!

Well if anyone is interested in getting them at the lowest possible price, email me I have FINALLY found the place that most of those ebay ppl are getting them, and then selling them for crazy prices.

BestHongKong.com makes a UV LED, but... I think that's more of a black light. I'm wondering if I should add amber as well. Eh, lets see how it goes with the cfl's and the big honkin' red lights.

I'll keep you all posted! GG

[SukonmiSkunk]

And SS, I don't know where you heard about the heat=resin thing, but I'm not entirely sure you're correct.

 

sure luke...

 

taken from here..

 

MJ Botany

 

some one has posted the transcript on OS too.. just search it..

 

but.. here it is.. under "Factors Influencing THC Production" .. scroll down about 2/3rds the way...

 

Many factors influence the production of THC. In general, the older a plant, the greater its potential to produce THC. This is true, however, only if the plant remains healthy and vigorous, THC production requires the proper quantity and quality of light. It seems that none of the biosynthetic processes operate efficiently when low light conditions prevent proper photosynthesis. Research has shown (Valle et al. 1978) that twice as much THC is produced under a 12-hour photoperiod than under a 10-hour photoperiod. Warm temperatures are known to promote metabolic activity and the production of THC. Heat also promotes resin secretion, possibly in response to the threat of floral desiccation by the hot sun, Resin collects in the heads of glandular trichomes and does not directly seal the pores of the calyx to prevent desiccation. Resin heads may serve to break up the rays of the sun so that fewer of them strike the leaf surface and raise the temperature. However, light and heat also destroy THC. In a drug strain, a bio-synthetic rate must be maintained such that substantially more THC is produced than is broken down. Humidity is an interesting parameter of THC production and one of the least understood. Most high-quality drug Cannabis grows in areas that are dry much of the time at least during the maturation period. It follows that increased resin produc. tion in response to arid conditions might account for increased THC production. High-THC strains, however, also grow in very humid conditions (greenhouses and equatorial zones) and produce copious quantities of resin. Cannabis seems not to produce more resins in response to dry soil, as it does to a dry atmosphere. Drying out plants by with-holding water for the last weeks of flowering does not stimulate THC production, although an arid atmosphere may do so. A Cannabis plant in flower requires water, so that nutrients are available. for operating the various bio-synthetic pathways.

[Luke Skywalker]

Hrm, I thought that was where I'd heard that before...

 

Sure I read somewhere that was a fallacy though. Wish I could remember where...

 

This is from Growers Guide by Mel and Ed...

Possible Advantages of Cannabinoid Production

 

1. Obviously the cannabinoids are psychoactive and physiologically active in many animals. This may dissuade plant-eating animals from eating the plant, especially the reproductive parts.

 

Many birds enjoy Cannabis seeds (guaranteed to make your canary sing). But in nature, birds will not bother young seeds, probably because they are encased in the cannabinoids-rich bracts. In wild or weedy plants, when the seed is mature it "shells out" and falls to the ground. Birds will eat the naked seeds. However, matured seeds are quite hard. Many will not be cracked and eventually will be dropped elsewhere, helping the plant to propagate. Bees and other insects are attracted to the pollen. The cannabinoids and resins may deter insects from feeding on pollen and developing seeds. Resin glands reach their largest size on the anthers (which hold pollen) and bracts (which contain the seed). {See plates 6, 7, 10 and 11.}

 

2. Terpenoid and phenolic resins are known to inhibit germination of some seeds. Cannabis resins may help Cannabis seedlings compete with other seedlings by inhibiting their germination.

 

3. Many of the cannabinoids (CBD, CBG, CBC and their acids) are highly active antibiotics against a wide range of bacteria (almost all are gram +) (36,130,184). Crude resin extracts have been shown to be nematocidal (36). (However, fungicidal activity is low.)

Most of the explanations you've probably heard for resin production from both lore and scientists have to do with physical factors such as sunlight, heat, and dryness. Presumably the resin coats the plant, protecting it from drying out under physical extremes. These explanations make little sense in light of the resins' chemistry.

 

The physical qualities of the glands and resins probably aid the plant in some ways. The sticky nature of resin may help pollen grains to adhere to the flowering mass and stigmas, or simply make the plant parts less palatable. And gland heads do absorb and reflect considerable sunlight, and so possibly protect the developing seed. For instance, gland heads are at first colourless (i.e., they absorb ultraviolet light). This screening of ultraviolet light, a known mutagen, may lower possible deleterious mutations. But physical properties seem to be secondary to the resins' chemical properties as functional compounds to the plant.

 

I would tend to follow Connel-Clarke on this more, it was a good treatment of cannabis for the time. There were some glaring errors in the genetics part of the thing, all just the way it was put rather than whether they understood what they were talking about, that just bit with me somehow... I'm sure more work has been done on the subject since these days, wasn't there a new "kick ass" taxonomic work on cannabis recently? I remember going, "holy shit that's expensive, but I'd kill to read it!"

 

Anyone who knows what the $@#% I'm talking about here just pipe up okay?

[Pam]

Well, I have my HPS ready just in case... But I'm really interested to see if these LEDs can do the trick. In a smallish box the heat was extreme with the HPS and with the 4 CFL floods and the led I'm at a constant 75 F which seems to please the mothers and clones.

The humidity can be a problem with soil because it can cause mold on the top of the soil. I've started to run the dehumidifier. It makes perfect sense that a dry atmosphere is better for growth. Even with my outdoor grows the high humidity levels here caused some bud mold towards the back where I couldn't reach to see.

Worse case I will end up switching to the HPS to flower, but my veg chamber is doing too well the way it is.

 

I DO believe the plants need a certain amount of warmth during flowering, and it's true that the LED doesn't do the trick...I'm still pondering this for a solution.

Well there's that site about led's I need to go see so I'll be back.

GG

[Pam]

That's a nice site! I can't wait to see how the little girls like the LED's and it's a great idea to have the heat rise from the HPS below!

I saw someone say the LED's were expensive, well if you go here, www.plasmaled.com this HAS to be where the ebay people are getting some of the lights.

I figured that my 12" round reds cost me under $50 shipping and all, and if they really last for 7-10 years...and they do the job... that's a bargain.

I'll be taking pix 4 you soon.

[Al B. Fuct]

The point is made by the sellers of led grow lights that lumens are a measurement of how the human eye sees light...not plants. and that 98% of the light put out by red and blue led's is used by the plant, as opposed to a much smaller percentage with HID lights. Therefore, because the plants can make use of more, they actually need less...

 

The point made by sellers of LED grow lights is that they'd like to sell you a very expensive LED grow light.

 

The point they omit is that the spectral output of LEDs is narrow because that's the compromise necessary due to the limits of semiconductor technology at the moment- not because they've tailored their LEDs' spectral output to a plant's needs. LED makers narrow the spectral bandwidth to increase the maximum luminous output. The broader the bandwidth, the more current must be run through the substrate- and many high-output types like Luxeon LEDs already require mounting on a metal-cored printed circuit board for cooling. The maximum current limitation is based the rate at which heat can be removed from the substrate before the semiconductor junction breaks down due to excessive heat.

 

Yes, all annual plants evolved in temperate latitudes respond to bluish and reddish portions of sunlight but do so (in concert with photoperiod) mainly as a means of telling what time of the year it is and how long it will be until winter. Early in the growing season, when the sun is higher in the sky, the average sunlight spectrum is stronger in the bluish region. As the summer season wears on and days shorten, with the sun peaking lower in the sky, sunlight is filtered through a greater thickness of atmosphere, which passes more red and filters out more blue. That doesn't mean that plants only need blue and/or red light. It means they will respond to a broad spectrum of light with peaks at certain frequencies (wavelengths) by growing in a particular habit. Bluish peaked spectra in concert with a long day photoperiod will encourage vegetative growth and red-orange peaked spectra in concert with a short day photoperiod will encourage flowering in annual plants.

 

Cannabis plants need high intensity light to produce weight and density in the buds. Knowing as we do that 'lumens don't add,' and knowing that a really good LED makes 150 lumens (albeit in a narrow, single colour spectrum), and knowing that 1500-1700 lumen CFLs produce thin, weedy buds... why on earth would you buy a large number of LEDs which only make 1/10 the intensity of CFLs?

 

A larger quantity of photons from a number of low intensity sources will not replace the high intensity required by cannabis plants. If you have one hundred 150 lumen LEDs, you will succeed in putting 150 lumens on 100 spots. You will not get high intensity light that will give you dense, heavy buds.

 

If you have a lot of lazy cash, sure, go have a play with LEDs. If you don't have a lot of lazy dough- and actually want to grow some dope- buy some proper HPS lights.

[godonacid]

al b. fuct go and have a look at the bloke on the advanced nutrients forum and check the plants he has done under leds, they are the way of the future there is no question, have a look at this link that was posted a page back.

HPS vs LED shootout