Lighting Metrics that Matter

[SGL D]

With all the numbers flying around regarding LEDs here are some metrics of value

PAR Light — Photosynthetically Active Radiation
Light between 400 and 700 angstroms (nanometers, 10^-8 meters)

PAR is for Plants, Lumens is for Humans
Not all PAR is useful

Terrestrial plants don't need a lot of green/yellow light to photosynthesize — just a little to stimulate caratenoids

Some evidence that UVA (315-400nm) and UVB light (280-315nm) helps cannabis growth

Most UVB light is absorbed by ozone layer — does not support additional UVB lamps in lights

Measuring PAR — Photosynthetic Photon Flux (PPF)
Measured as micro-moles (µ, or 10^-6) )of photons emitted per second
One Mole = 6.02 * 10^23 (Avagadro's Constant)

Photosynthetic Photon Flux Density (PPFD)
Micro-moles of photons emitted per square meter per second
Way more important to growers than PPF

An HID light might have huge PPF numbers at the bulb, but inverse square law of light means that the number of photons hitting a given area (PPFD) declines exponentially as the distance between the light source and the plant surface increases.

An LED light may emit very intense light but is so small that you have to raise it way off the canopy to get coverage

Daily Light Integral (DLI)
DLI = PPFD over the course of a light cycle

Measured as Moles of PAR photons per day
Example: a light emitting PPFD = 1000 running 12 hours emits a DLI = 43.2 moles/day
Computed as ((60 sec/min)*(60 min/hr)*(12 hrs/day)*(PPFD))/1 million

Current research indicates Cannabis grows best at PPFD = 1500 (DLI = 65) and temperature = 30 degrees C

Lighting Efficiency = PPFD/joule or PPFD/input watt
Measure of how well a light converts electrons to photons

Lights requiring supplemental AC or cooling fans will have very low numbers

Can also look at both purchase price per PPFD and five year cost per PPFD

How to Play Games With The Numbers

Report PPF (photons emitted by the bulb) rather than PPFD (photons hitting the plant)

Report readings at distances that would scorch a plant

Lights that emit intense PPF over a small area

Put reflective walls around the light to reflect the light back into the measurement area

Reporting overall PPFD for only a small portion of the growing area (Hot Spot)

Using inconsistent grid sizes

 

[iamcyclopseat]

Thanks for the informative post.

 

[SGL D]

Thanks for the heads up... I figured I would see how many light science geeks are out there. I love it.

4 x 4 grids, DLI and PPFD the only things growers really need for planning and buying decision.

Spectrums are tricky to trust... flower spectrums need to have adequate red photon energy.. the real trick is taking blue and making red without photon drop off

This is interesting too.... Current research indicates Cannabis grows best at PPFD = 1500 (DLI = 65) and temperature = 30 degrees C

 

[jasper19]

Bullshit from a light salesman. Plenty of info from studies done by universities if you take the effort to search. DLI of 25-30 is plenty. Show me a grow that is documented as well as the ones done by legitimate researchers of a grow at DLI of 60. Hell the plants would be cooked.

 

[Icemud]

Bullshit from a light salesman. Plenty of info from studies done by universities if you take the effort to search. DLI of 25-30 is plenty. Show me a grow that is documented as well as the ones done by legitimate researchers of a grow at DLI of 60. Hell the plants would be cooked.

He is correct in many ways, but also there is some info left out...

A DLI of 65 or 1500umol at 12/12 is the TOP end of optimal lighting (with added CO2). This is the point there more light will actually not add to photosytnthesis (saturation point). This is correct based on research which I will post below, and absolutely the best DLI/PPFD for the most optimal growing with co2.

For optimal conditions without CO2, you don't really want to exceed 1000-1100umol.

Most Sunlight hitting the earth surface is around 2000umol

Most sunloving plants according to Purdue University need a DLI of 22-30+

With DLI of 22, then at a 12/12 schedule the bottom level of optimal light for sun loving plants would be at about 510 umol/m2/s-1



This is about all the inforamtion that currently is available by major research that I have found...


So typically for light in flowering you want to see betweeen 500-1100 umol for optimal production without co2, and if you have a perfect environment, controlled temps and VPD, and added co2, then you want to be giving the plants 1500umol.





Effect of different photosynthetic photon flux densities (0, 500, 1000, 1500 and 2000 μmol m−2s−1), temperatures (20, 25, 30, 35 and 40 °C) and CO2 concentrations (250, 350, 450, 550, 650 and 750 μmol mol−1) on gas and water vapour exchange characteristics of Cannabis sativa L. were studied to determine the suitable and efficient environmental conditions for its indoor mass cultivation for pharmaceutical uses. The rate of photosynthesis (PN) and water use efficiency (WUE) of Cannabis sativa increased with photosynthetic photon flux densities (PPFD) at the lower temperatures (20–25 °C). At 30 °C, PN and WUE increased only up to 1500 μmol m−2s−1 PPFD and decreased at higher light levels. The maximum rate of photosynthesis (PN max) was observed at 30 °C and under 1500 μmol m−2s−1 PPFD. The rate of transpiration (E) responded positively to increased PPFD and temperature up to the highest levels tested (2000 μmol m−2s−1 and 40 °C). Similar to E, leaf stomatal conductance (gs) also increased with PPFD irrespective of temperature. However, gs increased with temperature up to 30 °C only. Temperature above 30 °C had an adverse effect on gs in this species. Overall, high temperature and high PPFD showed an adverse effect on PN and WUE. A continuous decrease in intercellular CO2 concentration (Ci) and therefore, in the ratio of intercellular CO2 to ambient CO2 concentration (Ci/Ca) was observed with the increase in temperature and PPFD. However, the decrease was less pronounced at light intensities above 1500 μmol m−2s−1. In view of these results, temperature and light optima for photosynthesis was concluded to be at 25–30 °C and ∼1500 μmol m−2s−1 respectively. Furthermore, plants were also exposed to different concentrations of CO2 (250, 350, 450, 550, 650 and 750 μmol mol−1) under optimum PPFD and temperature conditions to assess their photosynthetic response. Rate of photosynthesis, WUE and Ci decreased by 50 %, 53 % and 10 % respectively, and Ci/Ca, E and gs increased by 25 %, 7 % and 3 % respectively when measurements were made at 250 μmol mol-1 as compared to ambient CO2 (350 μmol mol−1) level. Elevated CO2 concentration (750 μmol mol−1) suppressed E and gs ∼ 29% and 42% respectively, and stimulated PN, WUE and Ci by 50 %, 111 % and 115 % respectively as compared to ambient CO2 concentration. The study reveals that this species can be efficiently cultivated in the range of 25 to 30 °C and ∼1500 μmol m−2s−1 PPFD. Furthermore, higher PN, WUE and nearly constant Ci/Ca ratio under elevated CO2 concentrations in C. sativa, reflects its potential for better survival, growth and productivity in drier and CO2 rich environment.

 

[SuperFunker]

Re PPFD, try this article

Home business Maximize Cannabis Growth @ 700, 1,500 or 2,000 µmol/m2/s? And, What About CO2?
Maximize Cannabis Growth @ 700, 1,500 or 2,000 µmol/m2/s? And, What About CO2?
January 17, 2017

How 'high' must Photosynthetic Photon Flux Density (PPFD, µmol/m2/s) be to induce peak photosynthesis in Cannabis? In 2008, Chandra measured a maximum rate of photosynthesis at 1,500 µmol/m2/s. In 2015, Chandra conducted a similar assessment and measured a maximum rate of photosynthesis at 2,000 µmol/m2/s. So, problem solved... right? Not necessarily.

Chandra, 2008.
Chandra's 2008 Cannabis analysis is a two part study. First, he measured the photosynthetic response to various light intensities at various temperatures. The light and temperature combination that produced peak photosynthesis was then applied to a series designed to gauge the photosynthetic response to various concentrations of CO2.

Part 1:

Cannabis strain "high yielding Mexican" sativa (in Chandra's other studies, "high yielding" means a high level of THC).
PPFD range 000, 500, 1,000, 1,500 and 2,000 µmol/m2/s.
Temperature range 20, 25, 30, 35 and 40 C.
CO2 350 µmol/mol (defined as ambient).
Humidity 55 % (+/-5 %).
At 30 C, the rate of photosynthesis started to level off above 1,000 µmol/m2/s, then peaked at 1,500 µmol/m2/s.
At 30 C, water use efficiency started to level off above 500 µmol/m2/s, then peaked at 1,500 µmol/m2/s.
Part 2:

Cannabis strain "high yielding Mexican" sativa (in Chandra's other studies, "high yielding" means a high level of THC).
PPFD 1,500 µmol/m2/s.
Temperature 30 C.
CO2 range 250, 350, 450, 550, 650 and 750 µmol/mol.
Humidity 55 % (+/-5 %).
Compared to the predefined ambient CO2 of 350 µmol/mol, a concentration of 250 µmol/mol inhibited net photosynthesis and depressed water use efficiency.
All CO2 concentrations above the predefined ambient of 350 µmol/mol, increased net photosynthesis and improved water use efficiency.
At 750 µmol/mol, net photosynthesis increased by 49.4 % and water use efficiency improved by 111.4 % over measurements observed at 350 µmol/mol.
The photosynthetic rate and water use efficiency produced at a CO2 concentration of 750 µmol/mol, don't represent peak responses. They appear to represent ceilings.
Chandra, 2015.
In 2015, Chandra repeated aspects of his 2008 study. This time, he measured the photosynthetic rate of four different Cannabis strains in response to various light intensities.

Cannabis strains "high THC yielding drug type" sativas (HPM, K2, MX and W1).
PPFD range 000, 400, 800, 1,200, 1,600 and 2,000 µmol/m2/s.
Temperature 25 C (+/-3 C).
CO2 350 µmol/mol.
Humidity 55 % (+/-5 %).
All four strains demonstrated their highest rate of photosynthesis at 2,000 µmol/m2/s. These results are not peak responses. They appear to be ceilings.
Water use efficiency among all four strains started to level off above 800 µmol/m2/s and peaked at 1,600 µmol/m2/s.
Above 1,600 µmol/m2/s, water use efficiency of K2 decreased, while W1, HPM and MX plateaued.
What's the answer? 1,500 or 2,000 µmol/m2/s?
Although a variety of Cannabis strains appear to thrive at very high levels of Photosynthetically Active Radiation (PAR), Chandra's analyses and results are constrained by his materials and methods. In both 2008 and 2015, Chandra used an LI-6400, 6400-01, 6400-02 Portable Photosynthesis System. The LI-6400-02 only produces light at 670 nm (+/-10 nm), so Chandra's results were exclusively induced by a narrow sliver of red light. Yes, quantum efficiency is greatest around 670 nm, but we all know a broad spectrum like the Zenith Bud Cultivator potentiates growth. Repeating Chandra's research with a broad spectrum may validate his results, but until then, Chandra has not yet fully rationalized the real life utility of broad spectrum light intensity as it applies to growing Cannabis.

What about 700 µmol/m2/s?
Putting aside the limitations of Chandra's results, reaping an average intensity of 2,000 µmol/m2/s with natural light isn't possible. And, although maintaining 2,000 µmol/m2/s over a typical 18 hour light cycle is possible with artificial light, it may not be cost-effective. So, what's a practical light intensity that's less than 2,000 µmol/m2/s? It seems that a tentative maximum may have already been rationalized. When Chandra studies Cannabis, he maintains a crop of test plants and relies on 700 µmol/m2/s in the following setup:

Area 335 to 350 square feet.
Lights 14 1,000 watt HID's with cooling fans attached to each.
Light height 3 to 4 feet from the canopy.
PPFD 700 µmol/m2/s (+/-24 µmol/m2/s) at the canopy.
Light cycles 18/6 and 12/12.
Temperature 25 C (+/- 3 C).
Humidity 55 % (+/-5 %).
Containers 30 cm diameter x 28 cm high.
Growth medium 11 of topsoil, sand and manure.
Ambient CO2 is assumed, because it's not mentioned.
Although the above doesn't probe the limits of Cannabis growth, I assume Chandra utilizes this setup, because it's an effective use of resources that produces a reasonable crop. So, if you replicate this environment and target 700 µmol/m2/s as a light intensity average, your grow has as much potential as Chandra's.

But Questions Remain.
With a slight modification, the question still remains... "What level of broad spectrum PPFD will induce peak photosynthesis in Cannabis?" To answer this, a broad spectrum light needs to be used to confirm/contribute to Chandra's research.

A question of greater importance... "How do broad spectrum light intensities and CO2 concentrations affect the photosynthetic rate of Cannabis?" Exploring this question may be more significant, because understanding responses to a range of PPFD and an associated range of CO2 will allow professionals to consider costs and benefits of investing in lights, gas or both. For example, this research could provide information to resolve and exploit a question like, "Will elevated concentrations of CO2 combined with a 'sub-maximal' light intensity of 700 µmol/m2/s stimulate photosynthesis?"

Improving Cannabis growth may be more cost-effective if coaxed by pumping gas, not by burning more lights. Many plants grown under moderate PPFD, develop greater biomass in an environment supplemented with CO2. Moreover, it's well known that elevated CO2 directly affects flowering plants by increasing the number and size of flowers. Light intensity is certainly critical, but elevated CO2 appears to further leverage cultivation. So, the obvious questions is, "What combination of broad spectrum PPFD and CO2 maximizes photosynthesis in Cannabis?"

Digging into the Details.
The above isn't an exhaustive exploration. If you know of additional scholarly Cannabis-specific research, please post the associated link in the comments. In the meantime, I urge you to personally examine Chandra's research and post comments, concerns, challenges, etc.

Photosynthetic response of Cannabis sativa L. to variations in photosynthetic photon flux densities, temperature and CO2 conditions (Chandra, 2008).
Photosynthetic response of Cannabis sativa L., an important medicinal plant, to elevated levels of CO2 (Chandra, 2011).
Temperature response of photosynthesis in different drug and fiber varieties of Cannabis sativa L. (Chandra, 2011).
Light dependence of photosynthesis and water vapor exchange characteristics in different high THC yielding varieties of Cannabis sativa L. (Chandra, 2015).

Source: Loudbank
By Richard Jones.

 

[Icemud]

I have over 125 DLI and my umols are 1300

a 125 DLI is 1445 micromoles/m2/s-1 at 24/0 schedule, and at 12/12 its double that, at 2893 micromoles/m2/s-1.

How did you come to those numbers? running longer than 24 hour days?

 

[Icemud]

I have a lighting passport spectrometer that can calculate DLI and PPFD, as well as showing the spectrum with or without the curve added in. I have measured my hybrid 1100 watt light at center plant height for that reading.
Parameter Value
PPFD (400~700 nm) 1400.4 μmol/㎡s
PPFD IR (701~780 nm) 158.23 μmol/㎡s
PPFD R (600~700 nm) 582.03 μmol/㎡s
PPFD G (500~599 nm) 432.02 μmol/㎡s
PPFD B (400~499 nm) 386.47 μmol/㎡s
PPFD UV (380~399 nm) 20.149 μmol/㎡s
YPFD (400~700 nm) 1190.1 μmol/㎡s
YPFD (380~780 nm) 1227.3 μmol/㎡s
YPFD IR (701~780 nm) 25.007 μmol/㎡s
YPFD R (600~700 nm) 533.03 μmol/㎡s
YPFD G (500~599 nm) 376.05 μmol/㎡s
YPFD B (400~499 nm) 281.16 μmol/㎡s
YPFD UV (380~399 nm) 12.111 μmol/㎡s
R/ B 1.51
R/ FR 3.68
DLI 121.00 mol/㎡
Illuminance
70233 lux

λp (380~780 nm) 428 nm
λD (380~780 nm) 0 nm
CCT 5152 K
CRI 86

Ok, that makes sense... the numbers above, but not the 1st set of numbers on the 1st post.

That means for a DLI of 121 you have to run 1400 micromoles intenstiy 24 hours a day, with no night period which is FARR TOO much light for vegging cannabis.

DLI of 65 should be about max for Cannabis.

 

[SuperFunker]

DLI should be based on average PPFD not peak, right?

 

[SuperFunker]

so then a single center measurement is a peak PPFD measurement, not average... ie, as you move away from the center, would expect the PPFD to fall...

 

[Icemud]

DLI should be based on average PPFD not peak, right?

Well yes and no...

The question is worded kind of odd, but yes... DLI is total light per day in mols/day.... so if the light intensity fluctuates it accounts for the change... however PPFD itself doesn't have "peaks" or "averages" as its an instantaneous reading of phonons per second, averaged over a square meter.... so technically PPFD doesn't have a "peak reading" and average reading, but just a single reading, and the single readings averaged over a 24 hour period is what determines DLI.

If that makes sense. lol

 

[Icemud]

They are flowering heavy under the hybrid side. My hydrofarm quantum par meter shows over 1300 umols but also only reads from 400-700nm and this light puts out energy above and below that.

So if you are flowering, then you are running 12/12 probably, and your reading of 1300 umols/m2/s-1 at a 12/12 schedule is a DLI of approximately 56...

You are at pretty much Ideal lighting for a 12/12 period

One thing though and its still heavily debated in the lighting world, but 400-700nm is technically the range of light that drives photosynthesis, some sources though argue its closer to 380nm-750nm. Most sources however accept 400-700 to be the PAR range or the range of light responsible for driving photosynthesis, light outside of this range generally is not accepted as wavelengths that drive photosythesis, however they do influence photomorphogeneis.



Nice grow by the way! very clean setup too!

 

[Icemud]

so then a single center measurement is a peak PPFD measurement, not average... ie, as you move away from the center, would expect the PPFD to fall...

It shouldn't if the lighting solution was designed/installed for the garden correctly... the PPFD should be uniform across the entire canopy, however most LED lighting manufactures don't design their lights this way, and still think in the HPS mindset (one single high power light above the plant). LED spreads light different than HID which is why most LED panels have really poor coverage, but are intense 5' away.. they are like spotlights or lasers.

A properly illuminated area should have near uniform PPFD anywhere you take a reading at canopy level.

 

[Icemud]

I hope you looked at my video of my LED , I have very uniform coverage by a light designed by me

You designed that? wow, nice work! I'm impressed! I'm running a very similar setup.. I made hybrid panels with 2 models of the budmasters I had, and combined them into 1 panel... so 1/2 of the panel is 3500k cobs and the other 1/2 is the god modules which are primarly 660nm osrams, a few mixed white ssls, and some blue ssls... pretty much an enhanced white full spectrum... and so far, amazed at how the plants love it.

My goal was to spread out the intensity of the Osram SSL LED's to even out the canopy PPFD and lessen hotspots, plus add more green light as its very underrated.

3 things really stuck out about your design I liked....

the hybrid white/mono spectrum... Me likey!

The push/pull air cooling design, very smart!

The contoured design of your led, its curved and not flat which really makes use of how LED's project! again very genius!

 

[SuperFunker]

so taking 2 measurements (1400 and 500 PPFD) the average is 950 PPFD... therein lies the challenge... in a small area, attaining a high average PPFD and assoc DLI is relatively easy, but in a larger area - like in Chandra's 350 square foot grow environment - high average PPFD becomes more of a challenge... note: average PPFD must also be detailed as a function of square meters... aside: when i measure average PPFD in a symmetrical grow like 4 x 4, i typically throw away the center value and the 4 corners, because they may skew the results...

regardless, good job McCree, nice to see humans exploring/experimenting with hardware and grow environments...

 

[Icemud]

so taking 2 measurements (1400 and 500 PPFD) the average is 950 PPFD... therein lies the challenge... in a small area, attaining a high average PPFD and assoc DLI is relatively easy, but in a larger area - like in Chandra's 350 square foot grow environment - high average PPFD becomes more of a challenge... Note: average PPFD must also be detailed as a function of square meters... aside: when i measure average PPFD in a symmetrical grow like 4 x 4, i typically throw away the center value and the 4 corners, because they skew the results...

The challenge isn't much of a challenge if you forget the "HID" knowledge and look outside the box in terms of using LED in all ways it can be used.... (not saying you are in the box) but since LED can be designed so many ways... that is the challenge of designing a LED to utilize its benefits, but not waste them... Most LED companies are stuck in the HID mentality, 1 single high powered light over a tray... and that is the issue... but....

Its all about innovative design... kind of like how McCree did his light... he has a fixture that is contoured, which is utilizing the direct beams of mono chips effectively.... and instead of creating a hotspot, he angled the panel to project the direct light outwards...

Its really more of a challenge for LED manufactures to come up with designs that stray away from HID thinking, and use LED to the full potential.


So for instance... in a 4x4 tent... most lighting companies would suggest 1 big 1200w LED over the center of the tent... which then would lead to readings like you mentioned... where the center might be 1000umol, and the sides only getting 200umol.... how I would recommend lighting is I would find out how many plants, how they are grown in the 4x4, how tall they get...etc... If it was 1 single plant in a 4x4 tent, then I would recommend generally a higher powered light above, and side lighting. IF it was a scrog or sea of green then I would recommend 4x smaller wattage panels, because not as much penetration is needed but uniform even lighting and intensity is key.... so its really about how lighting is applied which is the challenge of figuring it out... unless you can design your own lights to exact specs...

 

[SuperFunker]

Well yes and no...

The question is worded kind of odd, but yes... DLI is total light per day in mols/day.... so if the light intensity fluctuates it accounts for the change... however PPFD itself doesn't have "peaks" or "averages" as its an instantaneous reading of phonons per second, averaged over a square meter.... so technically PPFD doesn't have a "peak reading" and average reading, but just a single reading, and the single readings averaged over a 24 hour period is what determines DLI.

If that makes sense. lol

what i mean by peak PPFD is a single on center measurement as opposed to an average of 100 data points over a square meter

 

[SuperFunker]

The challenge isn't much of a challenge if you forget the "HID" knowledge and look outside the box in terms of using LED in all ways it can be used.... (not saying you are in the box) but since LED can be designed so many ways... that is the challenge of designing a LED to utilize its benefits, but not waste them... Most LED companies are stuck in the HID mentality, 1 single high powered light over a tray... and that is the issue... but....

Its all about innovative design... kind of like how McCree did his light... he has a fixture that is contoured, which is utilizing the direct beams of mono chips effectively.... and instead of creating a hotspot, he angled the panel to project the direct light outwards...

People would probably think I'm nuts if I told them that I'm working with a 600w panel with all (less than 1w chips) that is blowing away 1000w DE lights... but they are.... I can't say much about it since I'm under a NDA, but lets say the panel is designed to only be 5" away from the canopy and instead of wasting vertical space to allow the light to spread, an alternate design was created to give the same PPFD across the whole tray with less than a 100umol difference between high/low readings.

Its really more of a challenge for LED manufactures to come up with designs that stray away from HID thinking, and use LED to the full potential.

sounds like a Spydr (there are others that do same thing)... the challenge that i refer to is exactly what you are talking about; however, i look at it from a consumer perspective... ie understand the benefits of various platforms and use the platform that best suites your grow area... ex Spydr is great when you dont have height, while other LED units are well suited for angled delivery on long rows...

 

[Icemud]

what i mean by peak PPFD is a single on center measurement as opposed to an average of 100 data points over a square meter

You would want to figure out what the target PPFD of your plant is, for what light schedule, and then build the lighting to suit that need...

For instance... if you know you are flowering on a 12/12 schedule, and need 1500 micromoles for flowering for optimal DLI of 65, Then you would situate lights so the entire canopy is getting 1500micromoles.. so multiple datapoints or readings of PPFD would be what you want to see, all in the range of 1500micromoles... that means all 4 corners of the tent should be getting 1500micromoles, and the center shoudl be getting 1500micromoles.

Even though a PPFD reading is the average photons falling over a square meter, its designed for sunlight which does not drop off and remains constant whether you measure it where you stand, or walk 3' over and measure it... PPFD is assuming that the lighting is constant like the sun..... I don't know how to explain it though in terms of LED lights that fall off directly outside of the main beam projection as the lighting isn't uniform and constant in how it disperses.

I don't know how to explain it better so I hope this makes sense...

 

[Icemud]

Just got tired of all the bs from the lighting manufacturers telling me what's best and producing inferior products at inflated prices. I contacted a Chinese company and began working with them to build a better Led with a spectrum that took over a year to perfect and didn't really achieve that until I added the lec in. I use 90 degree lenses to get penetration but curved the design to spread par more evenly and I drive my Diodes at 600mA so they don't run hot and I haven't had a single one burn out , ever. The hybrid light has the two opposing fans removed and higher 55cfm fans installed by me and wired into the LED's , so the led switch turns them on and off the lec is remote dimmable from 300-400-630-700 watts with the LED's on or off as you like , so it makes this light very user friendly and energy saving, it can grow with your grow from veg to flower. My LED's have a 12 Band Spectrum 365nm-780nm and the device runs cool to the touch and takes minimal cooling other than the built in fans. I also run my grow at an average daytime temperature of 78-80f.

My LED is only 635 actual watts, by the way

Same reason I started testing LED's and learning everything I can about them. I got sick of seeing fly by night investors buy up stock from overseas and selling it at 5x markup to 'get rich' while they advertise lies and bs to growers that didn't know any better.

I wanted to give honest reviews, call out bs companies, and show the good ones while teaching factual lighting concepts to others... way too much mis information going on in LED lighting so I had to do something... so I started testing and if a light broke, or was crap, or if the company was full of lies, or the product sucked... I wanted the public to know... and I've called out quite a few companies over the years... some people and companies probably think I'm a PITA, but I know others appreciate it...LOL

Your spectrum is on point... I like how you considered the deep blue and uv region which most grow lights forget about, and that is the most important end for oils, terps and trichomes

I've been wanting to make my own growlights for a while, but realize that there is quite a bit of upfront investment involved so I haven't done it yet, plus more and more plant lighting research is coming out daily with LED's allowing for more accurate testing to be done, so I am putting it off for a while.

I have a few ideas still that I have yet to see in LED's which would solve the hotspot and "perfect fit" problems with "all in one" solutions that are currently on the market...