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Old 12-06-2018, 03:10 AM #1
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Information About Grow Light Spectrum, PAR, Photosynthesis, Leaf Surface Temperature

I put together a detailed thread on lighting terminology/science and photosynthesis on 12/5. I highly recommend reading to clarify the science of it all between HPS/MH, Double Ended HPS, CMH and Led.

Watching Canna Cribs and Growing Exposed episodes on youtube, I realized many licensed producers are running led fixtures. Licensed Growers can get rebates on the led fixtures up to 90% off MSRP through their power company for using less than 1000w lights, yielding the same or even more with higher terps and potency! If a facility running hundreds of lights can confidently switch completely over and boast improvement, there has to be some truth to the claims I figured.

Here is the company that specializes in grow lighting rebates for licensed producers, lighting quotes are free, your welcome!)
https://growrebates.com/

Those videos are why I started researching Led heavily and made the lighting information thread. Black Dog LED, Fluence and California Lightworks together have extensive research and testing published on their sites (for cannabis specifically even). I put the thread together using information from all 3 and HID light spectrum comparisons from Growers House, all very credible sources (along with additional research of my own).

From Black Dog LED Site:

"Various artificial grow light technologies create different light spectrums. LED grow lights differ significantly from other forms of artificial plant lights in that the spectrum can be tuned, eliminating unwanted excesses of light wavelengths (colors) while providing light plants can use most efficiently. Other artificial lighting technologies produce much of their light as an unintended and unavoidable byproduct of how they operate, ultimately wasting energy in heating up plant leaves.

When a photon of light hits a plant leaf, it can either be reflected or absorbed. Reflected photons will not affect the leaf temperature at all, but physics dictates that all photons absorbed by the leaf will increase the leaf temperature; how much depends on the energy (wavelength) of the photon and whether or not some of that energy was used to trigger other chemical reactions, such as photosynthesis. Photons fully utilized by the plant in chemical reactions will heat the leaf less than photons which are absorbed but not utilized. Therefore, measuring leaf surface temperature indirectly measures the efficiency of the light spectrum for growing plants-- less-efficient spectrums will tend to heat the leaf more, while more-efficient spectrums will heat the leaf less as more of the light energy is being converted to chemical energy.

High Pressure Sodium (HPS) in particular converts a significant portion of the energy consumed by the light directly to non-visible infrared light in the 810-830nm range, peaking about 819nm. This infrared light is perceptible to you (and plants) by the warmth it creates when exposed to the light. Additionally, much of the visible light HPS bulbs produce is yellow and not highly-utilized by plants. This radiation not used for photosynthesis or other chemical reactions only serves to heat up the leaves, requiring cooler ambient temperatures to keep the plants' leaves at their ideal temperature."

Link To Leaf Surface Temperature Full Study (Other Plant Results Than Cannabis Also):
https://www.blackdogled.com/lst

HPS Lamps have an interior wall temperature around 752 degrees Fahrenheit (400 Celsius), CMH Ceramic arc tubes can operate at higher temperatures over 1700 degrees Fahrenheit (927.67 Celsius) so they can be potential fire hazards. Many city and county safety codes are beginning to prohibit the use of HID systems in residential indoor grows due to the dramatic increase in “closet fires”. Roughly 75% of all the energy consumed by an HID lamp is emitted as heat, and most of that heat is in the form of Infra-Red (IR) radiation. So not only do HID systems require significant air-conditioning, but the high levels of IR heat the leaves without raising the air temperature, and this differential can cause localized heat stress, fox-tailing, and other heat related problems even when the room air temperature is in a safe range, Optimal leaf surface temperature is around 88f for cannabis, which under hps occurs around 75f ambient room temperature.

Here is a comparison of leaf surface temps between 1000w HPS and 750w led both at 24" above canopy at 75f and 84F ambient room temperatures. All images below were taken with the FLIR camera's color scale locked between 69 °F and 95 °F to allow for easier direct comparisons. In this color scale, blue and cyan correspond to temperatures in the 70-79 °F range, green, yellow and orange represent the 80-89 °F range, and red-orange, red and white indicate temperatures in the 90+ °F range.



Led doesnt emit all of the unnecessary extra light spectrum that plants cant utilize. The leaf surface temp is much lower at 75f ambient room temperature because more of the light is available for growth. Being able to run the grow room at a warmer 84f temp can also save on AC if you live in a warm area.

Reproducing This Experiment Yourself:

Leaf surface temperature in otherwise-identical conditions can be greatly influenced by the thickness of leaves and their pigmentation level, which depend on the conditions an individual plant has been exposed to up to that point. Using the same exact plants for all conditions in the experiment eliminates the possibility of this natural variation affecting the results. (This would also suggest using near consistent lighting from seedling/clone to harvest for strongest establishment.)

Keep in mind that relative humidity affects how much evaporative cooling can cool the leaf, and that relative humidity is relative to the temperature. If you have 50% relative humidity in a 75 °F room and just heat the air up to 84 °F, the relative humidity will drop to 37%, and evaporative cooling will have a greater effect on leaf surface temperature.

As you can see from our FLIR pictures, leaf surface temperature can vary significantly even within one leaf. Using an infrared thermometer to measure leaf surface temperature will only give the temperature at a single point. A FLIR camera gives you a better picture (literally) of the full temperature range over the leaves.

Here are a few light spectrums/comparisons and more information:

Natural Sunlight



Plants evolved over millions of years to best convert light energy into carbohydrates and sugars. The most readily available light from the sun is in the middle part of the spectrum which we see as green, yellow and orange. These are the primary frequencies that human eyes use. However, studies show that these are the least used light frequencies in plants. Most of the photosynthetic activity is in the blue and red frequencies. The main reason for this counter-intuitive use of light by plants seems to be related to early forms of bacteria and the evolution of photosynthesis. Photosynthesis first evolved in bacteria over millions of years in the primordial sea. This evolved in bacteria long before the appearance of more complex leafy plants. These early photosynthetic bacteria extensively used the yellow, green and orange middle spectrums for photosynthesis which tended to filter out these light spectrums for plants evolving at lower levels in the ocean. As more complex plants evolved they were left only with the spectrums not used by bacteria, mostly in the red and blue frequencies.

There are two forms of Chlorophyll, each has absorption peaks in both the red and blue spectrums and both reflect yellow and green giving plants their green color. Chlorophyll A is the primary photosynthetic pigment and most abundant, it has absorption peaks at 430nm blue and 662nm red. Chlorophyll B is an accessory pigment and has absorption peaks at 453nm blue and 642nm red.

Many manufacturers reference the absorption spectrum of chlorophyll A and B (shown next) which peak in the blue and red regions of the visible spectrum as the main reason for providing a purple spectrum.





^The action spectrum of photosynthesis was created from research that was performed in the 1970s by Drs. McCree and Inada and this work was fundamental in defining the range of photosynthetically active radiation (PAR). Prior to this research, very little work had been performed to determine how varying wavelengths of light influenced photosynthesis and plant growth. These researchers utilized filters to create monochromatic wavebands to determine the influence of light spectra on photosynthesis of single leaves using an assimilation chamber.

So why is there such a difference between the absorption spectrum and the action spectrum if chlorophyll is responsible for photosynthesis?

Recent work has shown that green light does promote photosynthesis in chlorophylls, quite efficiently in fact. Green light is able to penetrate deeper into leaf surfaces to drive photosynthesis in chloroplast located towards the bottom surface of the leaf, even more efficiently than red light at high PPFD. As PPFD increases, light energy that is absorbed in the upper chloroplasts tends to be dissipated as heat, while penetrating green light increases photosynthesis by exciting chloroplasts located deep in the mesophyll (Terashima et. al., 2009). Additionally, green light penetrates through leaf surfaces much better than red or blue light to reach the lower canopy, which is extremely important in dense canopy production techniques which are common in controlled environment agriculture.

Chlorophylls Are Not The Only Photoreceptors That Are Responsible For Photosynthesis!

There are other types of antenna photoreceptors which also utilize this spectrum range to promote photosynthesis, mainly the carotenoids. The carotenoid family consists of smaller families of pigments called carotenes and xanthophylls, The difference between the two groups is chemical: carotenes are hydrocarbons and do not contain oxygen, while xanthophylls contain oxygen. The two absorb different wavelengths of light during a plant’s photosynthesis process, carotenes are orange and xanthophylls are more yellow.

Carotenes contribute to photosynthesis by transmitting the light energy they absorb to chlorophyll. Carotene protects plant cells against the destructive effects of ultraviolet light and also has an important antioxidant function of deactivating free radicals — single oxygen atoms that can damage cells by reacting with other molecules. They also help to absorb the energy from singlet oxygen, an excited form of the oxygen molecule O2 which is formed during photosynthesis.

Xanthophylls are both accessory pigments and structural elements of light-harvesting complexes (Lhcs). Together with β-carotene, they act both as chromophores, absorbing light energy that is used in photosynthetic electron transport, and as photoprotectants of the photosynthetic apparatus from excess light and from the reactive oxygen species (ROS) that are generated during oxygenic photosynthesis.

So while the green/orange/yellow bands can be absorbed by other pigments like the Carotenoids, they are far less efficient. Over 50% of this spectrum range is reflected away and/or poorly utilized. Carotenoids are typically located deeper in the leaf because they get most of their photons from light that is reflected off the leaves and bounces deeper into the canopy to be absorbed through the bottom of the leaves.



Bulb Life Expectancy In different Lighting Systems:

Veg light running 16 hours per day = 5840 hours per year.

Bloom light running 12 hours per day = 4360 hours per year.

As time on goes on the spectrum of the bulbs become less optimal though they will produce the same amount of light. HPS bulbs are typically recommended to be replaced after 12 months of flowering use, MH bulbs typically recommended replaced after 8-9 months of use. CMH with stronger arc tubes and a square wave ballast are estimated to last longer.

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Old 12-06-2018, 03:11 AM #2
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Here is The Black Dog Led Spectrum from Leaf Temperature comparison:



Hortilux Super HPS 1000w Spectrum:



Double Ended HPS Spectrum Comparison:



3100k Ceramic Metal Halide Spectrum Comparison:



Samsung 3000k led Spectrum:


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Old 12-06-2018, 04:23 PM #3
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This is interesting. Thanks for explaining it.
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Old 12-06-2018, 04:29 PM #4
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Old 12-07-2018, 09:50 PM #5
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Samsung 2700k led Spectrum:



Lighting Terminology:

Electromagnetic Spectrum

The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 1025 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names. The electromagnetic waves in each of these bands have different characteristics, such as how they are produced, how they interact with matter, and their practical applications.

classified by radio, microwaves, terahertz waves, infrared, visible light, ultraviolet, X-rays, and gamma rays



Electromagnetic Radiation:

classified by radio, microwave, infrared, visible, ultraviolet, X-rays and gamma rays.

Full Spectrum Light:

Spectral range from Near Ultra violet 300nm to the end of the infrared spectrum 1000nm.

Ultraviolet Spectrum:

Spectral range from 10nm to 400nm.

Ultraviolet A (UVA) 315nm to 400nm

Ultraviolet B (UVB) 280nm to 315nm

Ultraviolet C (UVC) 100nm to 280nm

Near Ultraviolet Spectrum:

Spectral range from 300nm to 400nm

Visible Spectrum

The portion of the electromagnetic spectrum that is visible to the human eye. A typical human eye will respond to wavelengths from about 390nm to 700nm.

Infrared Spectrum:

Spectral range from 700nm to 1000nm (1mm)

Black Body:

A Black Body is reference to an opaque (unable to be seen through) and non reflective object which absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence.

Black Body Radiation:

Every object radiates (and absorbs) electromagnetic waves. The spectrum of this radiation is not dependent on the chemical composition of the matter but it's only determined by its absolute temperature T. It turns out that all objects behaves like blackbodies, regardless if they are actually black or not. At ambient temperature the majority of the emitted spectrum is in the long wave infrared which is not visible. As the temperature rises, the spectrum shifts towards shorter wavelengths, this is known as "Wien's shift". At temperatures around 900 K, part of the radiation becomes visible since wavelengths in the 700 nm region are present and the object start to appear "red hot".If you think of a blacksmith working a piece of hot iron, the iron glows red because its temperature is around 1'000 K, but the charcoal in the furnace glows the same color because it's at about the same temperature, even if carbon and iron are chemically very different.

The picture below shows a nail glowing red hot when heated with a propane torch: one can clearly see the hottest part of the nail glowing yellow, the part that is just outside the flame glowing red and the rest being black because normal cameras cannot see infrared radiation. The nice blue color of the flame is not due to blackbody radiation: the temperature of a propane torch is around 3'000 K so the flame should glow yellow, but the chemical reaction taking place emits a much stronger blue radiation masking the faint yellow glow.



CCT (Correlated Color Temperature):

CCT refers to the color of the light itself. CCT does not refer to the actual temperature of the light source; instead, it describes if you were to heat a black body to 2700 degrees Kelvin, and then compare it with a light source with a CCT of 2700K, you would notice both objects glow with the same color.

CRI (Color Rendering Index):

CRI refers to how a light source renders the colors of other objects and surfaces. The CRI can reach a maximum value of 100, which means the light source in question has the same color-rendering capability as natural daylight. Color rendering is increasingly distorted as the CRI becomes lower, and there is no lower limit: negative CRI values indicate extremely poor light sources that completely distort color perception.

Lumens:

The lumen is a unit of measure of the quantity of visible light emitted by a source, Lumens are weighted according to a model of the human eye’s sensitivity to various wavelengths. This weighting means that light in the green-yellow spectrum will register significantly higher in lumens than red or blue light – the most important colors for photosynthesis in plants. While lumens may reflect how much light humans perceive, they do not adequately account for how much light your plants are actually receiving.

Luminous Flux:

Luminous flux refers to how much light energy is emitted per unit of time in all directions, and is measured in lumens. To properly measure luminous flux, you would need to place your light in a device called an integrating sphere, which is able to measure all of the light that the source produces. Luckily, this value will be provided on the data sheet for your COB, so you can save the $10,000 you were going to buy the sphere with for something else. You can use luminous flux ratings to compare COBs against one another, so long as you have the voltage and current at which the reading was taken. If you compare 2 COBs and both are rated for 10,000 lumens, but one does it at 36 volts and 1 amp (36 watts), and the other does it at 36 volts and 1.5 amps (54 watts), the first one is more efficient and is a better choice.

Lux:

Lux is a measurement of how many lumens fall on a 1 square meter surface, when lit by a source 1 meter away. 1 Lux is 1 lumen per square meter. Lux meters can be purchased pretty cheap online, but again – these are measuring lumens, and aren’t very useful for grow lighting.

Foot Candles:

A foot candle is a measurement of how many lumens fall on a 1 square foot area, 1 foot away from the light source.

PAR (Photosynthetically Active Radiation):

PAR is not a measurement of light, but a range of a light that factors in all wavelengths from 400nm (blue) to 700nm (red). The PAR range corresponds with the range of light that’s visible to humans, PAR does not intentionally weight various wavelengths of light differently like lumens do.

PPF (Photosynthetic Photon Flux):

PPF is a measurement of the total number of photons a light source emits per second that are within the PAR range. PPF is measured in micromoles per second (µMol/S). 1 Micromole is equal to 602 quadrillion photons (602,000,000,000,000,000).

PPE (Photosynthetic Photon Efficacy/Micromole per Joule):

Photosynthetic Photon Efficacy refers to how efficient a horticulture lighting system is at converting electrical energy into photons in the PAR 400nm to 700nm wavelengths measured as umol/j.

PPE = PPF ÷ actual wattage, the higher the better.

Example:

an LED light draws 300 watts and advertises 540 PPF

540 ÷ 300 = 1.8 umol/j

PPFD (Photosynthetic Photon Flux Density):

This is the measurement given from PAR meters. PPFD measures the average amount of photons in the PAR range hitting a certain area per second, PPFD is measured in micromoles per meter squared per second μmol/m2/s. Full sun on a clear day at noon is ~2000 PPFD.

Many commercial grow lights provide PPFD values, but omit critical information like the distance at which the PPFD reading was taken. Taking a single measurement of PPFD is also not worth much either – it’s better to have multiple measurements of PPFD in several different places below the light.

To Find PPFD Example:

a light advertises 500 PPF or μmol/s at 24" height.

First find out how many square meters your space is.
a 3x3 space = 0.836127 square meters.

Then take your PPF or μmol/s and divide by your square meters.

500 PPF or μmol/s divided by 0.836127 = ~598 average PPFD in a 3x3 area.

DLI (Daily Light Integral):

DLI is a cumulative measurement of the total number of PAR 400nm-700nm photons that reach the plants in a day and is represented in mol/m2/d. Plant growth is determined by the DLI. A clear summer day is 50-60 mol/m2/d, highest yields from many crops seems to be around 43 mol/m2/d according to NASA experiments.

How to Determine DLI With Grow Lighting:

A light produces 1000 PPFD which is measured per second, there are 3600 seconds per hour.

1000 PPFD x 3600 seconds = 3600000 PPFD per hour.

Divide PPFD per hour by 1,000,000 to convert umols to mols.

3600000 ÷ 1000000 = 3.6 mols per hour.

multiply the mols per hour by number of hours the lights stay on each day

3.6 x 12 hours per day = DLI of 43.2 mols/m2/d which is ideal for maximum yields according to NASA experiments.

Here is a chart of average daily DLI in San Francisco Bay in March, April, May, June, July and August:



Here are daily DLI yield results from NASA biomass production chamber:


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Old 12-07-2018, 09:50 PM #6
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good job, i'll have to re read this a couple of times
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Old 12-09-2018, 03:25 AM #7
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Hortilux Daylight Blue MH:



Hortilux Dual Arc Spectrum:



Dimming HPS and MH example effect on spectrum:



CMH PAR meter measurements comparison from Growershouse at 24" height:
(averaged over area, final 5x5 is sum not averaged)

(The first bar surpassing every other CMH is the Philips Mastercolor CDM Elite 315W CMH Agro Lamp T12 - 3100K)



Issack did a hps vs cmh comparison thread using 4 Hotilux Super HPS 1000w and 4 630w dual lamp hoods with Philips Mastercolor CDM Elite 315W CMH Agro Lamp T12 - 3100K bulbs shown above as the best. Coco drain to waste fed multiple times per day with mills nutrients, 1000ppm co2 and ideal temperature, HPS side averaged about 1 gram per watt, Philips side had one lamp hit 2 grams per watt and the other 3 cmh around 1.4+ gram per watt.

Link To Thread

https://www.icmag.com/ic/showthread.php?t=352859

Increasing Potency With UV:
(From California Light Works and Black Dog LED)

Pictured Is 100nm to 1000nm



The Ultraviolet (UV) spectrum ranges from about 100 nanometers (nm) and 400 nm.

UVA, from about 315 nm to 400 nm, is an extension of the deep blue light spectrum and is included in most artificial light sources. Some level of photosynthesis occurs in this range.

UVB, from about 280 to 315, is somewhat damaging to plants in high levels and causes sunburns on humans. UVB causes damage in plants in much the same way as it damages human skin, and plants created defenses against UVB in the form of a protein called UVR8.

UVC, from about 100 nm to 280 nm is highly damaging to all living things. This is often used in sterilization and killing bacteria.

Photoreceptors like phytochromes mediate many aspects of vegetative and reproductive development and are responsible for absorbing UV, blue, red and far-red light. Cryptochromes, phototropins, and Zeitlupe (ZTL) are the three primary photoreceptors that mediate the effects of UV-A.

UV-B light is primarily mediated by the UV-R8 monomer. UVR8 is a protein molecule which senses UV, and then “tells” plant cells to change their behavior. Exactly how UVR8 molecules sense UV was recently discovered and is pretty interesting. UVR8 is what chemists call a “dimer,” which simply means that it’s made of two structurally similar protein subunits. When UV light hits the two protein subunits in UVR8, their charge weakens and they break apart. After the protein subunits break apart, they head to the cell nucleus to deliver their information. One of these changes caused by this reaction is very important in your cannabis garden. UV stress stimulates cannabis’ production of chemicals via the phenylpropanoid pathway, specifically malonyl-CoA and phenylalanine. Cannabis uses malonyl-CoA to make Olivtol, which it in turn uses to make THC. So finally the specific pathway which increases Cannabis potency when exposed to UV light is understood, and we can use this information to our advantage.

Safety Around UV in the Grow Room:

There is a threshold where the damage caused by high level UVB will exceed any benefits in potency, so caution and careful design protocols MUST be used when attempting to supplement UVB. It is also VERY important to be EXTREMELY careful using off-the-shelf UVB sources like lizard lights that are not specifically designed for human exposure, because while sunlight has quite high levels of UVB, the intensity of the sun prevents people from staring straight at it. UVB is invisible, so your eyes can’t tell you if they are getting too much UVB from a UVB light source in your grow room, and your eyes and skin can be damaged if the levels are too high.

Black Dog LED Says:

From our own research grows, Black Dog LED has demonstrated that UVA light alone can increase THC and CBD production in Cannabis plants. The UVA increases production of secondary metabolites such as THC, CBD, terpenes and flavonoids but without the negative effects of UVB light.
The combination of UVA and UVB light (from a standard "reptile bulb" fluorescent light) also increases THC and CBD production, but the inclusion of UVB in the light has noticeable detrimental effects on plant growth compared to only UVA.

From our experimentation, having about 3.5-4% UVA (as much as natural sunlight at noon) and 96-96.5% PAR light is about the right ratio for maximizing quality and canopy penetration without overly stressing the plants from too much UV. This is why we've engineered the Black Dog LED Phyto-Genesis Spectrum™ to only include UVA light, without any UVB wavelengths.

Link To Sources On UV:

https://californialightworks.com/uvb...d-thc-potency/

https://www.blackdogled.com/blogwhic...er-uva-or-uvb/

https://alliedscientificpro.com/web/...0White%20Paper

https://medicalmarijuanagrowing.blog...y-results.html

https://medicalmarijuanagrowing.blog...ana-study.html

https://medicalmarijuanagrowing.blog...c-and-cbd.html

https://medicalmarijuanagrowing.blog...-cannabis.html

https://onlinelibrary.wiley.com/doi/...1987.tb04757.x

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Old 12-11-2018, 03:27 AM #8
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Skoomd did alot of research and growing with multiple budget led lights before going DIY. He recommends the Roleadro brand on amazon as the best budget $70-$100 led fixtures and pulled 1.25+ grams per watt with 3 plants vegged for 8 weeks in a 2x4x5 grow tent. Comes with 30 day money back guarantee and 2 year warranty. The fans in these budget systems are known for failing early, Roleadro's customer service seems responsive from my looking into them. (probably good to have a backup light just in case you have to send it in for repair at some point.)

Here Is A Good Review/Overview Of Roleadro With Information On The Parts They Are Constructed With:

https://www.epicgardening.com/rolead...yhydro-review/

Here is the post from skoomd on budget led fixtures and their light spectrums and grow/yield results.

https://www.reddit.com/r/microgrower...yn&sh=a3e6469e

Viparspectra lights spectrum example:
(Completely missing the Chlorophyll A peaks at 430nm and 662nm)




Here is the MarsHydro 600 Spectrum:
(narrowly missing the Chlorophyll A peak at 430nm and moderately providing 662nm)


Quote:
Originally Posted by skoomd View Post
It was no where near as easy to pull a gram per watt under the marshydro as it was with the galaxyhydro/Roleadro, which always gave me at least 1g/w.


Here is the Roleadro 1000w (140w actual) that skoomd used and recommends, covers 2x2 area $98.99:
advertised is 845 ppfd 12" above canopy, 453 PPFD at 18" height.


https://www.amazon.com/Roleadro-Gala.../dp/B00PH1MQV8

Here is the spectrum for the Roleadro^:
(Includes UVA, Lots of intensity at the 662nm Chlorophyl A peak but narrowly misses the 430nm peak.)




Quote:
Originally Posted by skoomd View Post
For anyone curious, here's the 1.25 gram per watt run with the marshydro 600w and galaxyhydro 300w. Mind you, I paid 150$ shipped for both of those lights (sale on ebay). If I went with viparspectra, it would have costed over 250$ for the same watts.

And yes, that last pic is 2 foot+ long colas. Whoever said leds have poor light penetration knows nothing about lighting physics (more light sources + raised light height + reflective walls + wide beam spread = amazing light penetration)


The data Ive gathered from Black Dog Led grow yields suggests 350PPFD to 400PPFD average over a given area is good for 1 gram per watt, increasing to ~1.25 grams per watt ~500PPFD. At 930PPFD 1.56 grams per watt was achieved. I feel like this was more light than the plants could utilize without co2 supplementation or air exchange twice per minute at the least and could have yielded more considering it was twice the amount of light intensity needed for 1.25 grams per watt.

In my opinion DIY Samsung F series gen 3 3000k single row 24v Led strip builds on aluminum frame are the most efficient and can be built for around $1 per actual watt of draw. The F series' LM561C gen 3 diodes are the 2nd most efficient diode offered by Samsung in luminous efficacy behind the LM301b used in the V2 quantum boards.

F series have the most diodes per strip and multiple overlapping sources of light reduces loss over a given distance, so F series gen 3 can provide very even coverage and great canopy penetration. With his ~320w 10 strip build on a 24" x 32" frame in a 3x3 tent skoomd claimed 727PPFD even coverage at a height of 1 foot, 695PPFD even coverage at a height of 1.5 feet above the canopy, and finally 550PPFD even coverage at a height of 3 feet above the canopy.
Quote:
Originally Posted by skoomd View Post
That is unbelieveable. Shout out to the naysayers saying LEDs can't penetrate deeeeeeeeep down.
Skoomd and midwest toker are claiming ~1.9gpw currently with very similar builds.


Quote:
Originally Posted by skoomd View Post
my last grow where I pulled 18 ounces out of nearly the same sized space
Quote:
Originally Posted by skoomd View Post
Yeah the diodes are running exactly at 320w Do pretty much 2 grams a watt Just 1 in a 3x3 scrog.
Quote:
Originally Posted by Midwest Toker View Post
How about 1.9 gpw with 270 watts of LEDs or 18 ounces from a 3x4 under said wattage of LEDs.

Last edited by Ibechillin; 01-18-2019 at 07:27 PM..
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Old 12-11-2018, 10:29 AM #9
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Very useful and helpful information. Nice work.
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Old 12-11-2018, 10:51 PM #10
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Damn man I'm extremely impressed with these threads you're compiling together going to have to read the others later but much appreciated for these contributions SERIOUSLY
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