LED and BUD QUALITY

[greyfader]

The sun isn’t a good example for indoor single point lighting. For one the bottom of your plant will never be twice as far from the sun as the top. Indoors it’s the norm.

I also have a question for anyone that can answer. What is ppk?

hey buddy! i guess we still have cannabis as common ground. and, even though we've had our differences on issues not related to growing, i still respect you and wish you the best.

the ppk system is an experimental growing system i first designed mentally while in recovery from a liver transplant 15 years ago.

i had 13 years of traditional hydroponic experience before that, and 20 years of commercial salt-water marine specimen collecting, holding, and shipping, before that. so, lots of water experience.

i don't want to derail this thread but it is the system that produced the plants in the link in my signature below.

it is a recirculating, closed loop, soilless system that is highly redundant with overlapping fail-safes to prevent crop loss and is extremely conservative on both water and nutrient use.

it is a flow pattern that can be built to any scale. people have built miniatures in armoires and computer cabinets, small to medium ones in tents and bedrooms, basements, etc, and large warehouse operations.

i have operated 2 warehouse grows, one mine and one where i was the director of controlled environment growing for a large cbd corp.

i will be doing another, detailed, updated ppk thread soon showing the how-to and the theories. this time using led lighting.

i pulled some of the best pics from the thread "something wicked this way comes" under my former handle, delta9nxs, here on icmag.

 

[bloyd]

Anybody using temperature reduction at end of flower with LED's? If so how low? I'm finally able to control environment in a well insulated sealed room and have been dropping temps to upper 60s for finish and I feel I am getting better finished expressions but less weight.

@greyfader are you maintaining high temps for peak photosynthesis till finish?

 

[Rocket Soul]

thank you!

so, we are back on subject again.

you mentioned somewhere in the ancient past of this thread that you thought efficiency was over-rated.

i think that maybe there are different kinds of efficiency.

one is the straight-up conversion of electrical energy to par radiation.

another is the application of the photons in general.

so, there are two hypothetical lights, let's say they are both 1k watts.

but one has a linear arrangement of larger diodes on bars and one has a much greater number of smaller diodes that radiate outward in a circular pattern from multiple, overlapping, point sources.

we have discussed how the elimination of shading creates a greater illuminated surface.

what if the one that radiates outward from multiple point sources hits a greater surface area of the plant from more angles simultaneously than the one with larger diodes on linear bars?

would this not drive overall photosynthesis at a higher or equal rate?

even at a lower electrical efficiency, thereby offsetting the greater electrical efficiency of the other light?

Wow theres so much to bite down on in this one id have to jack the ripper and take it piece by piece. Theres a very real risk of wall of text rambling


You can have many different takes on efficiency, main ones being electrical and output per watt: lums (for human eyes, fairly irrelevant) varios photosynthetic active radiation (PAR) measures which basicly means photon count: standard range 400-700, extended 380 -780 (pbar, i think they call it) or weighted by how good the plant is at using the light by wavelength, by macree curve, think this one is called yPar iirc. Theres a few reasons to not think maccree curve is all there is too it: it was measured by suing individual wavelengths and not a full spectrum. That means you dont get an idea of how different parts of the spectrum interact making it more efficient as a whole: emmerson effect being one of them (interaction between light over and under 700nm give higher photosynthesis than sum of each of those intensities but even here theres more, the effect seems to work best with wavelengths 50nm apart, the best effect in 680 and 730nm).

The reason i think efficiency is over rated is that were not after photosynthesis per se, were after big yields of nice tasty potent buds.

This obviously relates very well with par intensity to the point most people seem to regurgitate Bugbees "spectrum doesnt matter" statement - which is patently false and a missinterpretation of his findings:
Spectrum doesnt matter in the spectrums that he studied. You can never prove negatives. And he was never very creative with those spectrums. I may be miss quoting him somewhat and more so quoting what people think he said.
The spectrums he compared wasnt very creatively conceived, generally standard whites with more or less extra red anf generally nothing below the blue spike of 450nm and unless adding far red almost nothing above 660. Thats 90nm out of 400 with minimal spectral coverage, missing various important action spectrum peaks.
So in my book you need atleast something there, preferably covering bioreactive peaks in action spectrums to even have a good chance at growing good weed. Problem is that doing so means losing efficiency which is what sells lights nowadays. People dont add UV diodes (which are usally actually violets with some uv) but this will always drop efficiency no matter how efficient the diode is: the further towards that end the less photons in one watt of light output. Higher energy photons will always mean less photons per watt. Similar with the +660 range but basicly down to historically inefficient diodes.

Some studies ive seen added a really nice measure which was light utilization efficiency:
How much bud you get per umol of dli. And what do you know, differences of up to around 15% with some more horti leaning spectrums. Thats a big deal. It would take a middling efficiency of 2.4ppf/w and give it the performance of a 2.75 ppf/w with quality benefits aswell.

Weve tried these odd diodes with our grow and had good results, in various ways but id like to resume them most as "growbro": just generally better smells and grows looking "better" to an experienced eye.

If you subscribe to the idea that there are absolute ideal light conditions, even if they are strain dependant, of intensity and spectrum, then efficiency is not in itself the measure for a really great grow light, only how many watts it takes to get there.

If you go for a light which is purely or mostly efficiency first you will never get to that ideal grow situation no matter how many watts you spend. If you try to get a good compromise between efficiency and spectrum, making sure that nothing plant related goes uncovered in the par region and just beyond all you need is to add a few more watts to your grow to get superior results. The extra yield from getting your spectrum really productive will make up for the extra watts you need to get your intensity up. And it seems like these spectrum effects are even more noticeable the higher you go in intensity. Im now in the horti spectrum at 40 or more watts per square foot available camp


On your hypothetical bar versus big spread out board light: this efficiency is a bit more like what migro measures, ppfd/w, the actual results of spread, wattage and efficiency at cannopy levels. And yes diffused light tends to be better as you surmise but the problem with the big round board light is that it will hotspot in the centre since edges dont recieve the same cross light. And the hotspot, centre intensity compared to edges, tend to only get worse the higher you have to hang it. If you keep it real low but at appropriate intensity you get more even light on cannopy. What you described is just really a board, theres ways to get it more even by asymmetric diode density, you can check those vypar bar lights for an idea. Or the 2 driver centre perimeter approach that i think i inboxed you some time ago (or maybe in your thread?)

I did it again, sorry, its a wall of text.

Im going to dropp of, my 5yo nephew just pulled a to the metal sound track of a Lego advert and im so proud

 

[Hiddenjems]

Wow theres so much to bite down on in this one id have to jack the ripper and take it piece by piece. Theres a very real risk of wall of text rambling


You can have many different takes on efficiency, main ones being electrical and output per watt: lums (for human eyes, fairly irrelevant) varios photosynthetic active radiation (PAR) measures which basicly means photon count: standard range 400-700, extended 380 -780 (pbar, i think they call it) or weighted by how good the plant is at using the light by wavelength, by macree curve, think this one is called yPar iirc. Theres a few reasons to not think maccree curve is all there is too it: it was measured by suing individual wavelengths and not a full spectrum. That means you dont get an idea of how different parts of the spectrum interact making it more efficient as a whole: emmerson effect being one of them (interaction between light over and under 700nm give higher photosynthesis than sum of each of those intensities but even here theres more, the effect seems to work best with wavelengths 50nm apart, the best effect in 680 and 730nm).

The reason i think efficiency is over rated is that were not after photosynthesis per se, were after big yields of nice tasty potent buds.

This obviously relates very well with par intensity to the point most people seem to regurgitate Bugbees "spectrum doesnt matter" statement - which is patently false and a missinterpretation of his findings:
Spectrum doesnt matter in the spectrums that he studied. You can never prove negatives. And he was never very creative with those spectrums. I may be miss quoting him somewhat and more so quoting what people think he said.
The spectrums he compared wasnt very creatively conceived, generally standard whites with more or less extra red anf generally nothing below the blue spike of 450nm and unless adding far red almost nothing above 660. Thats 90nm out of 400 with minimal spectral coverage, missing various important action spectrum peaks.
So in my book you need atleast something there, preferably covering bioreactive peaks in action spectrums to even have a good chance at growing good weed. Problem is that doing so means losing efficiency which is what sells lights nowadays. People dont add UV diodes (which are usally actually violets with some uv) but this will always drop efficiency no matter how efficient the diode is: the further towards that end the less photons in one watt of light output. Higher energy photons will always mean less photons per watt. Similar with the +660 range but basicly down to historically inefficient diodes.

Some studies ive seen added a really nice measure which was light utilization efficiency:
How much bud you get per umol of dli. And what do you know, differences of up to around 15% with some more horti leaning spectrums. Thats a big deal. It would take a middling efficiency of 2.4ppf/w and give it the performance of a 2.75 ppf/w with quality benefits aswell.

Weve tried these odd diodes with our grow and had good results, in various ways but id like to resume them most as "growbro": just generally better smells and grows looking "better" to an experienced eye.

If you subscribe to the idea that there are absolute ideal light conditions, even if they are strain dependant, of intensity and spectrum, then efficiency is not in itself the measure for a really great grow light, only how many watts it takes to get there.

If you go for a light which is purely or mostly efficiency first you will never get to that ideal grow situation no matter how many watts you spend. If you try to get a good compromise between efficiency and spectrum, making sure that nothing plant related goes uncovered in the par region and just beyond all you need is to add a few more watts to your grow to get superior results. The extra yield from getting your spectrum really productive will make up for the extra watts you need to get your intensity up. And it seems like these spectrum effects are even more noticeable the higher you go in intensity. Im now in the horti spectrum at 40 or more watts per square foot available camp


On your hypothetical bar versus big spread out board light: this efficiency is a bit more like what migro measures, ppfd/w, the actual results of spread, wattage and efficiency at cannopy levels. And yes diffused light tends to be better as you surmise but the problem with the big round board light is that it will hotspot in the centre since edges dont recieve the same cross light. And the hotspot, centre intensity compared to edges, tend to only get worse the higher you have to hang it. If you keep it real low but at appropriate intensity you get more even light on cannopy. What you described is just really a board, theres ways to get it more even by asymmetric diode density, you can check those vypar bar lights for an idea. Or the 2 driver centre perimeter approach that i think i inboxed you some time ago (or maybe in your thread?)

I did it again, sorry, its a wall of text.

Im going to dropp of, my 5yo nephew just pulled a to the metal sound track of a Lego advert and im so proud

When I went from single light growing in tents to multiple lights on the ceiling in an array my coverage from a 1000w light went from 4x4 to 5x5. That was a huge increase in yield per light.

 

[Rocket Soul]

When I went from single light growing in tents to multiple lights on the ceiling in an array my coverage from a 1000w light went from 4x4 to 5x5. That was a huge increase in yield per light.

We get good coverage from around 480w for a 1x 1.3m in an open space, which is about 2 square feet short of a 4x4. Yield from 650 - 750 per tray. Walkway on 2 sides of the grow, tray arranged in rows. 1000w in a 4x4 tent sounds like a lot to me, double what we use. 1000w per 5x5 with over lapp should be around 1000ppfd, close to maxing out.

 

[Rocket Soul]

hey buddy! i guess we still have cannabis as common ground. and, even though we've had our differences on issues not related to growing, i still respect you and wish you the best.

the ppk system is an experimental growing system i first designed mentally while in recovery from a liver transplant 15 years ago.

i had 13 years of traditional hydroponic experience before that, and 20 years of commercial salt-water marine specimen collecting, holding, and shipping, before that. so, lots of water experience.

i don't want to derail this thread but it is the system that produced the plants in the link in my signature below.

it is a recirculating, closed loop, soilless system that is highly redundant with overlapping fail-safes to prevent crop loss and is extremely conservative on both water and nutrient use.

it is a flow pattern that can be built to any scale. people have built miniatures in armoires and computer cabinets, small to medium ones in tents and bedrooms, basements, etc, and large warehouse operations.

i have operated 2 warehouse grows, one mine and one where i was the director of controlled environment growing for a large cbd corp.

i will be doing another, detailed, updated ppk thread soon showing the how-to and the theories. this time using led lighting.

i pulled some of the best pics from the thread "something wicked this way comes" under my former handle, delta9nxs, here on icmag.

Even for a die hard coco dtw grower the ppk design can give some benefits:
We tried to build a tailpipe into one of our standard pots, to see how much water retention we could remove by eliminating the perched water table. It would retain about 2/3ds of the water compared to the no tailpipe pot. The idea is that either increased watering frequency or increased pot size would increase our yield. Still have to test it out but pretty sure we got a project for the future.

 

[Ca++]

Wow theres so much to bite down on in this one id have to jack the ripper and take it piece by piece. Theres a very real risk of wall of text rambling


You can have many different takes on efficiency, main ones being electrical and output per watt: lums (for human eyes, fairly irrelevant) varios photosynthetic active radiation (PAR) measures which basicly means photon count: standard range 400-700, extended 380 -780 (pbar, i think they call it) or weighted by how good the plant is at using the light by wavelength, by macree curve, think this one is called yPar iirc. Theres a few reasons to not think maccree curve is all there is too it: it was measured by suing individual wavelengths and not a full spectrum. That means you dont get an idea of how different parts of the spectrum interact making it more efficient as a whole: emmerson effect being one of them (interaction between light over and under 700nm give higher photosynthesis than sum of each of those intensities but even here theres more, the effect seems to work best with wavelengths 50nm apart, the best effect in 680 and 730nm).

The reason i think efficiency is over rated is that were not after photosynthesis per se, were after big yields of nice tasty potent buds.

This obviously relates very well with par intensity to the point most people seem to regurgitate Bugbees "spectrum doesnt matter" statement - which is patently false and a missinterpretation of his findings:
Spectrum doesnt matter in the spectrums that he studied. You can never prove negatives. And he was never very creative with those spectrums. I may be miss quoting him somewhat and more so quoting what people think he said.
The spectrums he compared wasnt very creatively conceived, generally standard whites with more or less extra red anf generally nothing below the blue spike of 450nm and unless adding far red almost nothing above 660. Thats 90nm out of 400 with minimal spectral coverage, missing various important action spectrum peaks.
So in my book you need atleast something there, preferably covering bioreactive peaks in action spectrums to even have a good chance at growing good weed. Problem is that doing so means losing efficiency which is what sells lights nowadays. People dont add UV diodes (which are usally actually violets with some uv) but this will always drop efficiency no matter how efficient the diode is: the further towards that end the less photons in one watt of light output. Higher energy photons will always mean less photons per watt. Similar with the +660 range but basicly down to historically inefficient diodes.

Some studies ive seen added a really nice measure which was light utilization efficiency:
How much bud you get per umol of dli. And what do you know, differences of up to around 15% with some more horti leaning spectrums. Thats a big deal. It would take a middling efficiency of 2.4ppf/w and give it the performance of a 2.75 ppf/w with quality benefits aswell.

Weve tried these odd diodes with our grow and had good results, in various ways but id like to resume them most as "growbro": just generally better smells and grows looking "better" to an experienced eye.

If you subscribe to the idea that there are absolute ideal light conditions, even if they are strain dependant, of intensity and spectrum, then efficiency is not in itself the measure for a really great grow light, only how many watts it takes to get there.

If you go for a light which is purely or mostly efficiency first you will never get to that ideal grow situation no matter how many watts you spend. If you try to get a good compromise between efficiency and spectrum, making sure that nothing plant related goes uncovered in the par region and just beyond all you need is to add a few more watts to your grow to get superior results. The extra yield from getting your spectrum really productive will make up for the extra watts you need to get your intensity up. And it seems like these spectrum effects are even more noticeable the higher you go in intensity. Im now in the horti spectrum at 40 or more watts per square foot available camp


On your hypothetical bar versus big spread out board light: this efficiency is a bit more like what migro measures, ppfd/w, the actual results of spread, wattage and efficiency at cannopy levels. And yes diffused light tends to be better as you surmise but the problem with the big round board light is that it will hotspot in the centre since edges dont recieve the same cross light. And the hotspot, centre intensity compared to edges, tend to only get worse the higher you have to hang it. If you keep it real low but at appropriate intensity you get more even light on cannopy. What you described is just really a board, theres ways to get it more even by asymmetric diode density, you can check those vypar bar lights for an idea. Or the 2 driver centre perimeter approach that i think i inboxed you some time ago (or maybe in your thread?)

I did it again, sorry, its a wall of text.

Im going to dropp of, my 5yo nephew just pulled a to the metal sound track of a Lego advert and im so proud

Wow theres so much to bite down on in this one id have to jack the ripper and take it piece by piece. Theres a very real risk of wall of text rambling


You can have many different takes on efficiency, main ones being electrical and output per watt: lums (for human eyes, fairly irrelevant) varios photosynthetic active radiation (PAR) measures which basicly means photon count: standard range 400-700, extended 380 -780 (pbar, i think they call it) or weighted by how good the plant is at using the light by wavelength, by macree curve, think this one is called yPar iirc. Theres a few reasons to not think maccree curve is all there is too it: it was measured by suing individual wavelengths and not a full spectrum. That means you dont get an idea of how different parts of the spectrum interact making it more efficient as a whole: emmerson effect being one of them (interaction between light over and under 700nm give higher photosynthesis than sum of each of those intensities but even here theres more, the effect seems to work best with wavelengths 50nm apart, the best effect in 680 and 730nm).

The reason i think efficiency is over rated is that were not after photosynthesis per se, were after big yields of nice tasty potent buds.

This obviously relates very well with par intensity to the point most people seem to regurgitate Bugbees "spectrum doesnt matter" statement - which is patently false and a missinterpretation of his findings:
Spectrum doesnt matter in the spectrums that he studied. You can never prove negatives. And he was never very creative with those spectrums. I may be miss quoting him somewhat and more so quoting what people think he said.
The spectrums he compared wasnt very creatively conceived, generally standard whites with more or less extra red anf generally nothing below the blue spike of 450nm and unless adding far red almost nothing above 660. Thats 90nm out of 400 with minimal spectral coverage, missing various important action spectrum peaks.
So in my book you need atleast something there, preferably covering bioreactive peaks in action spectrums to even have a good chance at growing good weed. Problem is that doing so means losing efficiency which is what sells lights nowadays. People dont add UV diodes (which are usally actually violets with some uv) but this will always drop efficiency no matter how efficient the diode is: the further towards that end the less photons in one watt of light output. Higher energy photons will always mean less photons per watt. Similar with the +660 range but basicly down to historically inefficient diodes.

Some studies ive seen added a really nice measure which was light utilization efficiency:
How much bud you get per umol of dli. And what do you know, differences of up to around 15% with some more horti leaning spectrums. Thats a big deal. It would take a middling efficiency of 2.4ppf/w and give it the performance of a 2.75 ppf/w with quality benefits aswell.

Weve tried these odd diodes with our grow and had good results, in various ways but id like to resume them most as "growbro": just generally better smells and grows looking "better" to an experienced eye.

If you subscribe to the idea that there are absolute ideal light conditions, even if they are strain dependant, of intensity and spectrum, then efficiency is not in itself the measure for a really great grow light, only how many watts it takes to get there.

If you go for a light which is purely or mostly efficiency first you will never get to that ideal grow situation no matter how many watts you spend. If you try to get a good compromise between efficiency and spectrum, making sure that nothing plant related goes uncovered in the par region and just beyond all you need is to add a few more watts to your grow to get superior results. The extra yield from getting your spectrum really productive will make up for the extra watts you need to get your intensity up. And it seems like these spectrum effects are even more noticeable the higher you go in intensity. Im now in the horti spectrum at 40 or more watts per square foot available camp


On your hypothetical bar versus big spread out board light: this efficiency is a bit more like what migro measures, ppfd/w, the actual results of spread, wattage and efficiency at cannopy levels. And yes diffused light tends to be better as you surmise but the problem with the big round board light is that it will hotspot in the centre since edges dont recieve the same cross light. And the hotspot, centre intensity compared to edges, tend to only get worse the higher you have to hang it. If you keep it real low but at appropriate intensity you get more even light on cannopy. What you described is just really a board, theres ways to get it more even by asymmetric diode density, you can check those vypar bar lights for an idea. Or the 2 driver centre perimeter approach that i think i inboxed you some time ago (or maybe in your thread?)

I did it again, sorry, its a wall of text.

Im going to dropp of, my 5yo nephew just pulled a to the metal sound track of a Lego advert and im so proud

Efficiency can rub off on us another way. If we go from a middling 2.7umol to a leading 3umol, that is over 10% more light, for the same power consumption. Do that to 10 lights, and we save enough electricity for an 11th light, and some fans around it. That is 10% more yield, or the yield of one whole light, if you prefer. 10% more crop might easily pay for the more expensive lights, in one hit. After which, you have 7 years of hits to come. So for somebody who's power usage limits grow size, that 3umol light is worth every penny.

That is how I saw the HID to LED conversion. Yes, it cost bloody thousands. Then a couple of months later, it paid them thousands back. So I never felt the pain. It was just a good investment, that took a few months to start coming in, for years.


Who was doing 13h days? I just read it this week. On at 9 and off at 22. I know some have posed the idea 13.2h is the limit, but I'm wondering if that is LED. My thoughts go to the far red effects on getting to sleep quicker. An LED light is generally without, and tent walls are cold, with their very low thermal mass. I suspect HID crops in rooms, may get to sleep quicker than LED in a tent. I'm looking for examples.

Oh, did I mention the bungee on my washing machine valve, that might click 4 times a day


No.. sorry.. the 13h and if it helps (with presumably broad leafs) with LED, and no far red for fast sleeping.

 

[Scfarmer]

So I'm week 8 of flower of my second LED grow, thought I'd share a pic of the Blue dream sherbet that is furthest along. Maybe a week left and il take the tops off and let the kids go upto week 10

 

[Rocket Soul]

Efficiency can rub off on us another way. If we go from a middling 2.7umol to a leading 3umol, that is over 10% more light, for the same power consumption. Do that to 10 lights, and we save enough electricity for an 11th light, and some fans around it. That is 10% more yield, or the yield of one whole light, if you prefer. 10% more crop might easily pay for the more expensive lights, in one hit. After which, you have 7 years of hits to come. So for somebody who's power usage limits grow size, that 3umol light is worth every penny.

That is how I saw the HID to LED conversion. Yes, it cost bloody thousands. Then a couple of months later, it paid them thousands back. So I never felt the pain. It was just a good investment, that took a few months to start coming in, for years.


Who was doing 13h days? I just read it this week. On at 9 and off at 22. I know some have posed the idea 13.2h is the limit, but I'm wondering if that is LED. My thoughts go to the far red effects on getting to sleep quicker. An LED light is generally without, and tent walls are cold, with their very low thermal mass. I suspect HID crops in rooms, may get to sleep quicker than LED in a tent. I'm looking for examples.

Oh, did I mention the bungee on my washing machine valve, that might click 4 times a day
View attachment 19083937

No.. sorry.. the 13h and if it helps (with presumably broad leafs) with LED, and no far red for fast sleeping.

I agree. The point is it seems like you can gain 10% in par efficiency going one way, while the other way, optimizing plant response in the form of light utilization (g of harvest per umol of dli) can also gain 10-15% in yield. The study is pages behind ill see if i can dig it out, it also showed other benefits (significant higher terps, improvements in smell/flavour profiles, bringing back volatile smells) of going for a more horticentric approach.
Also, in the very end, of all the growers i know and see online (big time comercial is almost never around here): noone seems completely watt limited, more so space limited. If you want to bring your yearly results up (total crop values; yield, cycle time and quality)and have a hard time doing so with standard HE lights it may be better to go spec for 40w per square foot or even higher (you never have to use those extra watts if you dont want and need) and take a little extra yield + the other benefits.

Not asking telling anyone to stop believing efficiency is a good thing, it obviously is but there is more to it. What do you say to the home grower that grows his own smoke but want higher quality: do you think he prefers his 300w light for his 3x3 with great yields and decent quality or a 350w light with same to bigger yield, great smells and quality in the end after cure, plants looking happier and easier to grow all the way thru grow? Im betting there is a place in the market at least for this type of thinking. People really seems to like to stop growing mids and grow like a boss. No offense to your grow, it looks point. Also, I mean youre own mixed grow with hps and leds seems to indicate that you were wanting more and found a way? I hope to show that there is yet another way.
My gear is in development and hopefully growing after xmas. I hope to get at least one local grower on as a tester for this not to be one mouth shouting but to have some more support, enough at least for peeps to have a look at it. I also got my own "grow guru" onboard as a tester: hes got over 30 years of growing and breeding experience with the best setup and results ive seen or heard of. Keeps the original genetics of Delicatessen seed bank which he contributed with: his genetics are just 4 generations from mexico/himalaya etc. He generally keeps of the forums nowadays but his promised me at least something in terms of growlog for this.

Im really keen to see how that one pans out cause it would a very good side by side situation.

The way im going is for strips but i might do some boards later, should drop into standard qb heat sinks. Thats just dropping in a board into your system, not a whole as expensive grow setup. But all i good time

 

[Scfarmer]

I agree. The point is it seems like you can gain 10% in par efficiency going one way, while the other way, optimizing plant response in the form of light utilization (g of harvest per umol of dli) can also gain 10-15% in yield. The study is pages behind ill see if i can dig it out, it also showed other benefits (significant higher terps, improvements in smell/flavour profiles, bringing back volatile smells) of going for a more horticentric approach.
Also, in the very end, of all the growers i know and see online (big time comercial is almost never around here): noone seems completely watt limited, more so space limited. If you want to bring your yearly results up (total crop values; yield, cycle time and quality)and have a hard time doing so with standard HE lights it may be better to go spec for 40w per square foot or even higher (you never have to use those extra watts if you dont want and need) and take a little extra yield + the other benefits.

Not asking telling anyone to stop believing efficiency is a good thing, it obviously is but there is more to it. What do you say to the home grower that grows his own smoke but want higher quality: do you think he prefers his 300w light for his 3x3 with great yields and decent quality or a 350w light with same to bigger yield, great smells and quality in the end after cure, plants looking happier and easier to grow all the way thru grow? Im betting there is a place in the market at least for this type of thinking. People really seems to like to stop growing mids and grow like a boss. No offense to your grow, it looks point. Also, I mean youre own mixed grow with hps and leds seems to indicate that you were wanting more and found a way? I hope to show that there is yet another way.
My gear is in development and hopefully growing after xmas. I hope to get at least one local grower on as a tester for this not to be one mouth shouting but to have some more support, enough at least for peeps to have a look at it. I also got my own "grow guru" onboard as a tester: hes got over 30 years of growing and breeding experience with the best setup and results ive seen or heard of. Keeps the original genetics of Delicatessen seed bank which he contributed with: his genetics are just 4 generations from mexico/himalaya etc. He generally keeps of the forums nowadays but his promised me at least something in terms of growlog for this.

Im really keen to see how that one pans out cause it would a very good side by side situation.

The way im going is for strips but i might do some boards later, should drop into standard qb heat sinks. Thats just dropping in a board into your system, not a whole as expensive grow setup. But all i good time

I'm a home grower who went from chasing yeild ( moving from 600 HID to 1000HID) then coming to the conclusion that yeild isn't everything I switched to CMH because LEDs were still fairly new or very expensive.
Now I am searching for what will grant me that top shelf quality. Getting everything dialed in , eventually I will switch from big pot Coco to some form of hydro system. God knows I'm fed up of the buying and disposal of Coco.

 

[Rocket Soul]

I'm a home grower who went from chasing yeild ( moving from 600 HID to 1000HID) then coming to the conclusion that yeild isn't everything I switched to CMH because LEDs were still fairly new or very expensive.
Now I am searching for what will grant me that top shelf quality. Getting everything dialed in , eventually I will switch from big pot Coco to some form of hydro system. God knows I'm fed up of the buying and disposal of Coco.

For me its all of the above: highest cropp value per year: combo of yield, quality and if you can shorten your cycle somewhat. But i think at least where i am there is a need to be at the very top few percent of quality or your gear will be in a race to the bottom as these markets flood with mid class bud. Seems like a pattern repeating in every "green rush" region; here in my region it was really kickstarted by covid lockdowns and a "move to the countryside" trend.

Of course light is only part of it but why not push this part as well as everything else?

 

[greyfader]

Anybody using temperature reduction at end of flower with LED's? If so how low? I'm finally able to control environment in a well insulated sealed room and have been dropping temps to upper 60s for finish and I feel I am getting better finished expressions but less weight.

@greyfader are you maintaining high temps for peak photosynthesis till finish?

i've played around with it a little bit but not enough to come to any conclusions. my thinking is that maybe the last 3 days should be in the dark and mid 60's. i intend to try it on my next run.

temperature is the second most powerful regulator of plant metabolism after light so i think that if you do it while the plant is still bulking you will negatively affect yield.

 

[Hiddenjems]

For me its all of the above: highest cropp value per year, combo of yield, quality and if you can shorten your cycle somewhat. But i think at least where i am there is a need to be at the very top few percent of quality or your gear will be in a race to the bottom as these markets flood with mid class bud.

Of course light is only part of it but why not push this part as well as everything else?

My market niche locally is top shelf quality at prices a little higher than mids.

My growing strategy is based around getting high quality/low yield strains to finish faster and yield more without touching quality. I can’t sell mids to my customers.

 

[Rocket Soul]

My market niche locally is top shelf quality at prices a little higher than mids.

My growing strategy is based around getting high quality/low yield strains to finish faster and yield more without touching quality. I can’t sell mids to my customers.

Fast finisher without shitty quality is gold! Weve got some down to 7 weeks. Apparently fast finish (at least in sativas) is a fairly dominant trait, at least what i heard, generally passed on. Our genetic source had 6 weeks but it isnt enough to build decent yields. One of our phenos finished fadter rhan 7 but so nasty it wasnt worth smoking. It wasnt even low quality, it was tasting like hooverbag.
So keep a hold of your cuts that works and try to see if you can work them with other gentics.
Our fast finish apparently comes from an old mystery sativa cut called La Bella from reunion island.

 

[Hiddenjems]

Fast finisher without shitty quality is gold! Weve got some down to 7 weeks. Apparently fast finish (at least in sativas) is a fairly dominant trait, at least what i heard, generally passed on. Our genetic source had 6 weeks but it isnt enough to build decent yields. One of our phenos finished fadter rhan 7 but so nasty it wasnt worth smoking. It wasnt even low quality, it was tasting like hooverbag.
So keep a hold of your cuts that works and try to see if you can work them with other gentics.
Our fast finish apparently comes from an old mystery sativa cut called La Bella from reunion island.

I started out selfing “elite cuts” for multiple generations selecting for short flowering time.

Your results seem in-line with what I see. 7 weeks is about the fastest I can have anything done that’s still killer quality and a decent yield.

I’ve been able to manipulate a faster finish, but they are what I call micro-bud structure. The quality was still great.

 

[Charles Dankens]

Chill led
Click pic for sharp image

 

[greyfader]

Wow theres so much to bite down on in this one id have to jack the ripper and take it piece by piece. Theres a very real risk of wall of text rambling


You can have many different takes on efficiency, main ones being electrical and output per watt: lums (for human eyes, fairly irrelevant) varios photosynthetic active radiation (PAR) measures which basicly means photon count: standard range 400-700, extended 380 -780 (pbar, i think they call it) or weighted by how good the plant is at using the light by wavelength, by macree curve, think this one is called yPar iirc. Theres a few reasons to not think maccree curve is all there is too it: it was measured by suing individual wavelengths and not a full spectrum. That means you dont get an idea of how different parts of the spectrum interact making it more efficient as a whole: emmerson effect being one of them (interaction between light over and under 700nm give higher photosynthesis than sum of each of those intensities but even here theres more, the effect seems to work best with wavelengths 50nm apart, the best effect in 680 and 730nm).

The reason i think efficiency is over rated is that were not after photosynthesis per se, were after big yields of nice tasty potent buds.

This obviously relates very well with par intensity to the point most people seem to regurgitate Bugbees "spectrum doesnt matter" statement - which is patently false and a missinterpretation of his findings:
Spectrum doesnt matter in the spectrums that he studied. You can never prove negatives. And he was never very creative with those spectrums. I may be miss quoting him somewhat and more so quoting what people think he said.
The spectrums he compared wasnt very creatively conceived, generally standard whites with more or less extra red anf generally nothing below the blue spike of 450nm and unless adding far red almost nothing above 660. Thats 90nm out of 400 with minimal spectral coverage, missing various important action spectrum peaks.
So in my book you need atleast something there, preferably covering bioreactive peaks in action spectrums to even have a good chance at growing good weed. Problem is that doing so means losing efficiency which is what sells lights nowadays. People dont add UV diodes (which are usally actually violets with some uv) but this will always drop efficiency no matter how efficient the diode is: the further towards that end the less photons in one watt of light output. Higher energy photons will always mean less photons per watt. Similar with the +660 range but basicly down to historically inefficient diodes.

Some studies ive seen added a really nice measure which was light utilization efficiency:
How much bud you get per umol of dli. And what do you know, differences of up to around 15% with some more horti leaning spectrums. Thats a big deal. It would take a middling efficiency of 2.4ppf/w and give it the performance of a 2.75 ppf/w with quality benefits aswell.

Weve tried these odd diodes with our grow and had good results, in various ways but id like to resume them most as "growbro": just generally better smells and grows looking "better" to an experienced eye.

If you subscribe to the idea that there are absolute ideal light conditions, even if they are strain dependant, of intensity and spectrum, then efficiency is not in itself the measure for a really great grow light, only how many watts it takes to get there.

If you go for a light which is purely or mostly efficiency first you will never get to that ideal grow situation no matter how many watts you spend. If you try to get a good compromise between efficiency and spectrum, making sure that nothing plant related goes uncovered in the par region and just beyond all you need is to add a few more watts to your grow to get superior results. The extra yield from getting your spectrum really productive will make up for the extra watts you need to get your intensity up. And it seems like these spectrum effects are even more noticeable the higher you go in intensity. Im now in the horti spectrum at 40 or more watts per square foot available camp


On your hypothetical bar versus big spread out board light: this efficiency is a bit more like what migro measures, ppfd/w, the actual results of spread, wattage and efficiency at cannopy levels. And yes diffused light tends to be better as you surmise but the problem with the big round board light is that it will hotspot in the centre since edges dont recieve the same cross light. And the hotspot, centre intensity compared to edges, tend to only get worse the higher you have to hang it. If you keep it real low but at appropriate intensity you get more even light on cannopy. What you described is just really a board, theres ways to get it more even by asymmetric diode density, you can check those vypar bar lights for an idea. Or the 2 driver centre perimeter approach that i think i inboxed you some time ago (or maybe in your thread?)

I did it again, sorry, its a wall of text.

Im going to dropp of, my 5yo nephew just pulled a to the metal sound track of a Lego advert and im so proud

excellent reply! thank you and don't worry about "walls of text". i like walls of text. that's how i learn.

this light i built just to test the limits of how much light the plant can actually use in a 12 hour period.

it was 4' in diameter with 120 14 watt bulbs on approx 4" centers. 1680 watts.

it produced, without the skirt on, 1500 umols at 30 ".

with the skirt on 1500 umols at 36".

the difference between the dead center hotspot and the outermost band was approx 600 umols. too much so i removed 16 bulbs from the center and, with the skirt on evened out the flow to where the differences were less than about 250 umols.

this light has two 60 bulbs circuits, one inner and one outer. which i found useful at different stages of the grow.

i had another light set up with 72 bulbs in a square pattern. 6" centers one direction and 5" centers the other direction.

it would produce 1500 umols at about 16".

i'm sure most here are familiar with the famous paper done at the U of Miss by dr el sohley and co.

in this paper he found that the maximum rate of photosynthesis with cannabis occurs at 1500 umols of light flow and 86F or 30c with 750 ppm co2 supplementation.

his graphs showed a linear increase in photosynthetic rate as the light increased until you hit 1500 umols.

at that point, even with increasing light flow up to 2000 umols, the rate did not increase. it plateaued from 1500 to 2000 and then, above 2000, it plummeted straight down like falling off a cliff.

there were several obvious flaws in the paper. one was that he did all measurements on plant leaves only in integrating spheres.

another was that he only tested co2 up to 750 ppm.

but, in general, the paper was taken as gospel by most cannabis growers who were aware of it at the time.

below these 2 lights i had 2 clones of the same strain. they were sharing the same nutrient reservoir and were under identical enviromental conditions.

i set the lights so that both plants were getting 1500 umols at the top center.

during veg i ran 12 hour photoperiods, one on one plant and then the other 12 hour period on the other plant, alternating. this did not induce flowering because the spillover light was enough to stop it.

so theoretically, this provided 64.8 mols per period to each plant.

about 3 weeks into this veg period i noticed that the plant under the 120 bulb fixture was stunted compared to the plant under the 72 bulb fixture.

i was using all 5000k bulbs at this time.

so, it became obvious that one plant was getting a far greater total number of photons than the other plant, even at the same top dead center reading.

too many for too long of a period.

64.8 mols per diurnal period is one hell of a lot of light. more than most sites on earth provide. i'm including the famous jim faust insolation maps to illustrate.

only a few places reach that level of light per day and for only a few months.

my experimenting has brought me to the conclusion that 35-45 mols per day will grow a cost effective large plant.

1000 umols for 12 hours is 43.2 mols per period. delivered at a rate the plant can adequately process without going into some type of light avoidance or inhibition mode.

when running my hps rooms at around 1200 umols i would notice, about 8 hours into the period that the plants leaves that had been at attention, flat and facing the light, would start to droop slightly. i think i have seen this on time lapse also.

we used to call it "hitting the wall".

so, why build a fixture that will produce more light than needed? isn't this another way of increasing electrical efficiency?

i think my newer versions that i will use in the new thread, will produce 1000 umols at approx 12".

well, enough rambling for tonight.

 

[Scfarmer]

Fast finisher without shitty quality is gold! Weve got some down to 7 weeks. Apparently fast finish (at least in sativas) is a fairly dominant trait, at least what i heard, generally passed on. Our genetic source had 6 weeks but it isnt enough to build decent yields. One of our phenos finished fadter rhan 7 but so nasty it wasnt worth smoking. It wasnt even low quality, it was tasting like hooverbag.
So keep a hold of your cuts that works and try to see if you can work them with other gentics.
Our fast finish apparently comes from an old mystery sativa cut called La Bella from reunion island.

That's one thing I've been searching for! So many years of crappy sub par genetics has been really depressing. I must have tried multiple clones from a friend as well as multiple seeds of different strains from seed banks and so far I've only found one Mimosa that really kicks ass.
I'm hoping something comes from these Amnesia seeds bank seeds but I'm not so confident at the moment that they will stay in rotation.
If anyone has some suggestions for a super quality 8-9 week strain to try next I'd be very happy.

 

[Prawn Connery]

Good questions,
reminds me of a debate about two different ways of thinking about lightning for cannabis and plants in general.
Which is "better" ideally, a point source light or diffuse lightning?
So in nature it comes down to clear sky vs cloud layer.
My thinking would be about intensity of light needed for ideal photosynthesis, like is 100% sunlight the optimum or is it too much? Can a clouded day be better for the plant?
So naturally the same goes for lightning, the HPS(closer to point source) vs LED bars(diffuse) debate and tribalism etc...
Never ending story

Cheers

The sun isn't really a single point of light. Most of the sun's rays that hit the earth are – to all intents – parallel They are not "strictly" parallel, but when you measure the distances involved – coupled by the fact the sun is 100x the diameter of the earth and all of its surface emits lights – they might as well be.

The shadows and oblique angles cast by a HID inside a grow room are much higher than the light that reaches an outdoor plant.

The other thing most people forget is that sunlight is – for the most part – side-lighting. It's almost never directly overheard – it traces an arc on the horizon – and while the top of the plant gets lit, so does the side facing the sun.

 

[Prawn Connery]

Anybody using temperature reduction at end of flower with LED's? If so how low? I'm finally able to control environment in a well insulated sealed room and have been dropping temps to upper 60s for finish and I feel I am getting better finished expressions but less weight.

@greyfader are you maintaining high temps for peak photosynthesis till finish?

Yes, flowering at around 27C and finishing off under aircon at around 18-20C. I'm not doing it, but a friend of mine is with lights and clones provided by me and the results have been good. He cures at that lower temperature and it usually takes 2-3 weeks for the plants to fully dry. We also keep our finished produce in the fridge at 4C. It makes a big difference.

Sorry for the Instagram photos, but I don't keep photos on my computer. You can see everything here if you wish: https://www.instagram.com/growlightsaustralia/