CMH vs LED vs HPS

[Ca++]

so, the dli map for july should be the most intense month and also after about the 21st, the solstice, flowering begins.

1000 umols for 12 hours is 43.2 moles but outdoors the plant usually does not get that much sustained over a 12-hour period. it would be nice to see an hourly plot of a typical day.

the light intensity builds up, peaks, and then goes back down. along with the increasing intensity there is increasing temperature. both drive up and then down the metabolic rate.

my point is that the intensity is not static but is dynamic and constantly changing, intensifying and then lessening.

saturating the photosynthetic apparatus and then allowing time to process the synthase.

indoors we apply the light statically for a prescribed period and i'm thinking that we should be using a lower dli with leds than with hid lighting because of the multi-point nature of leds.

the extremely wide diode beam angles plus the multi-point distribution of the emitters have to be driving a higher metabolic rate overall than an equivalent hid light even with the same par meter spot reading at the top of the plant.

the led fixtures radically reduce the shaded surface area.

several people earlier in this thread said that they got excellent led yields with about 750 umols for the 12-hour period.

that would be 32.4 moles per day.

i have, over the last year, done some high dli grows like 1500 umols for 12 hours which is 64.8 moles per period.

i think it over-saturated the plants and stunted the top flowers. i got better flowers 6-8" down from the tops.

i also did a couple of grows with an 8-hour photoperiod but, again, i used 1500 umols which is 43.2 moles, and got better top flowers but i thought they should have been larger.

so, i'm just about to apply 1100 umols for 8 hours which is 31.68 moles per period.

i'm using all 2700k led bulbs plus a few 25-watt incandescents for flower.

we'll see what happens.

I guess a 1000umol average, if over 12 hours, would be a mid day peak that couldn't be used for long. There just isn't the co2 outside for that.

1800umol perhaps.
co2 timing/loading comes to mind. I'm not a greenhouse or co2 guy though.
Some interesting light hour work you are doing. I still wonder if we can get away from the 24 hour day.

 

[Corpselover Fat]

Not on the HLG, I have on the cheap light. The cheap light is keeping plants happy better for me than the Diablo R has..

Diablo R uses Samsung LM301H (white) and LH351Hs (red)..

Cheap led uses Bridgelux def not top bin.

They essentially the same spectrum. Differences must come from intensity, right?

 

[Ca++]

Have you checked the light levels under the diablo and cheap light? The diablo is just white lm301b in4000k(?) and some 660's.

Edit: looks like the cheap one also is 4000k whites and some 660's.

Perhaps it was another thread where I replied to this.
This light has narrow prominent peaks in the blue and the 660. These are not desirable traits.
I spoke about the double peak blues, which are used in offices now, to reduce the eye strain problems a single high peak causes. Also the photo-bleaching that peaky lights cause. It's a bit of a dot-to-dot game, but the pieces are there for further study. There are many other pieces in the game, and they all seem to fit. Though all these light spectrums needs grouping together for a real comparison.

 

[Corpselover Fat]

Nerhaps it was another thread where I replied to this.
This light has narrow prominent peaks in the blue and the 660. These are not desirable traits.
I spoke about the double peak blues, which are used in offices now, to reduce the eye strain problems a single high peak causes. Also the photo-bleaching that peaky lights cause. It's a bit of a dot-to-dot game, but the pieces are there for further study. There are many other pieces in the game, and they all seem to fit. Though all these light spectrums needs grouping together for a real comparison.

Both of their lights have the same peaks. Besides... you can grow with blurples and they only have the peaks.

 

[Hammerhead]

They essentially the same spectrum. Differences must come from intensity, right?

I don't really trust anything mentioned fro the cheap LED info.. It does grow well. I have it dimmed to 450w but will do 830w max.

The diablo is 630w max.

SAMSUNGS NEW EVO DIODE. LM301H EVO Mint White

https://download.led.samsung.com/led/file/resource/2023/04/Samsung-Lighting-Catalog_230405_10129400040606.pdf

 

[Ca++]

Both of their lights have the same peaks. Besides... you can grow with blurples and they only have the peak

I'm not sure where you are looking for the data. If the similarity is them both being 4000K plus some 660s, then that's not really enough to separate them.

 

[Corpselover Fat]

I'm not sure where you are looking for the data. If the similarity is them both being 4000K plus some 660s, then that's not really enough to separate them.

Their specs. Now I don't know if the cheap one's specs are correct, but using 4000k whites and 660 reds is common. One of them (hlg ) might produce more light. The cheap one is a bar fixture while hlg uses small boards, which are much more concentrated. The boards should(/might?) project the light in more intense beams than the bars.

 

[Cerathule]

Photobleaching is mostly a matter of too much light & heat influx, and only secondarily related to spectrum. There are lightbands that cause this more, but used at the right flux, none will.

There were alot of older type lampds like CFL, some HIDS they all have these "spikes" which are lines were specific elements release photons.

Also, Chandra measured still an increase of photosynthesis rate even beyond 2000 PPFD, with his Mexican Sativa (an outdoor strain). At ambient CO2 levels.

I think DLI indoors and outdoors is a different thing for the plant, the sun doesn't loose strength with a meter distance, so it stands to reason an outdoor plant in a sunny day gets way more Carbon. I mean there are these sunny cloudless days were the sun is up for 15h or so.

 

[Ca++]

I have also seen studies where plants kept going, north of 1500umol. We don't do it though, as growth increases per light quota are becoming very small. For atmospheric co2, even 1000umol isn't really valid. Unless you must maximise yield with a plant count limit.
For this reason, it should be better to run 1000umol for 12 hours, than run through the day with a curve like the sun provides. Presuming a DLI in the low 40s is the aim.

Photobleaching isn't something we see outdoors. We may have 1800umol but still not the bleaching we see at lower light levels, when using light in bands. Some plants will bleach at 650umol when using pink light, yet add in the other colours, and you can stop the bleaching at any realistic intensity. There is no requirement for heat, as we once thought as HID growers. Photo-bleaching research has mostly been about outstanding red, as red is a great colour to grow with, as it's cheaper to make. The more reds we can pack into a light unit, the higher the ppf. Which is a number that sells them. Lights used in 500umol commercial grows can have quite a bit of red. As the power gets turned up, the red peak must be reduced though. At high intensity, you simply can't use the pink lights you can for veg. Then as we get to extreme levels, we must level out the spectrum of even white looking lights. Different plant processes respond differently to different colours. Many of these processes must work together. I did know the full story of red, but forget. It was something about the electrons in the chlorophyll spinning up with masses of energy, that couldn't be processed or lost quick enough to be sustained. So the chlorophyll molecule collapsed.

I don't tend to remember the exact science, as it won't help me grow plants, any more than remembering sources. I just know what interests me about banded lighting.

I know it's about our eyes, but think about the new energy star requirement for double blues. They are making an LED with the same colour balance, but using two smaller blue peaks, not one large one. The only gain, is our eyes don't get damaged so much.
If we look at the blue light tests of late, blue has been bad. We don't need to look to know it was a mono-band light though. Biological systems are showing us again and again, that they don't like narrow bands. We can't excite one process, with little regard for the others. We started with red&blue (thanks nasa) but we are constantly moving away from it. Many towards the sun. Where the peaks are gone.

 

[Crooked8]

Photobleaching is mostly a matter of too much light & heat influx, and only secondarily related to spectrum. There are lightbands that cause this more, but used at the right flux, none will.

There were alot of older type lampds like CFL, some HIDS they all have these "spikes" which are lines were specific elements release photons.

Also, Chandra measured still an increase of photosynthesis rate even beyond 2000 PPFD, with his Mexican Sativa (an outdoor strain). At ambient CO2 levels.

I think DLI indoors and outdoors is a different thing for the plant, the sun doesn't loose strength with a meter distance, so it stands to reason an outdoor plant in a sunny day gets way more Carbon. I mean there are these sunny cloudless days were the sun is up for 15h or so.

This was tested and it was directly related to far red. Plants at the same intensity of 1000ppfd under 70+% blue had NO photobleaching vs the lights with more far red had tons. Both leds. Intensity is not what is causing the bleaching according to that study at USU.

 

[Crooked8]

Day 18, got the second trellis on and trained everything into it, took time but well worth it. Now ill focus on bringing the ppfd up. Currently running at 75%/540w per fixture. Ill go up 5-10% in the next few days and then up to fully cranking by day 28. This room is full but not overstuffed

 

[greyfader]

I guess a 1000umol average, if over 12 hours, would be a mid day peak that couldn't be used for long. There just isn't the co2 outside for that.

1800umol perhaps.
co2 timing/loading comes to mind. I'm not a greenhouse or co2 guy though.
Some interesting light hour work you are doing. I still wonder if we can get away from the 24 hour day.

it would be relatively easy to use 8 on, 12 off as your entire day. this would cut 17.66% off the total flowering time. so, with a 9-week strain, you have 63 days at 12/12 but 8/12 would be 11.1258 days off that
and should finish in 51.87 days.

a cheap Nearpow timer from Amazon has a repeat cycle function and you could set that to control lights rather than use a more expensive totally programmable timer.

it is limited to 15 amps @ 120v but you can use a dtdp relay from automation direct to use the timer to switch a bunch of 240v lights. the relays are 40 amp rated up to 600v.

but i think i'm seeing a stronger or more aggressively flowering plant using 8/16. also, i think it enhances terps or at least preserves them better than a 12-hour dark period.

about the mid-day sun intensity i have taken my meter outdoors in the deep south on a clear summer day and it will peg the meter which only goes up to 2000 umols.

 

[Crooked8]

it would be relatively easy to use 8 on, 12 off as your entire day. this would cut 17.66% off the total flowering time. so, with a 9-week strain, you have 63 days at 12/12 but 8/12 would be 11.1258 days off that
and should finish in 51.87 days.

a cheap Nearpow timer from Amazon has a repeat cycle function and you could set that to control lights rather than use a more expensive totally programmable timer.

it is limited to 15 amps @ 120v but you can use a dtdp relay from automation direct to use the timer to switch a bunch of 240v lights. the relays are 40 amp rated up to 600v.

but i think i'm seeing a stronger or more aggressively flowering plant using 8/16. also, i think it enhances terps or at least preserves them better than a 12-hour dark period.

about the mid-day sun intensity i have taken my meter outdoors in the deep south on a clear summer day and it will peg the meter which only goes up to 2000 umols.

Have you done an 8/16 cycle before and seen that rapid increase in ripening rate? Ive heard that the extra dark hours do increase ripening but i heard it was minimal.

You mentioned before you had plants where the terminal colas were smaller than budsites below. What was your ppfd at the time and how close were your fixtures? Ive seen that issue with HPS in the past when my lights were too close. Havent experienced that with leds at all though.

 

[Ca++]

I was just reading 2000umol is about it outdoors. The grower had found 1% more light, gave 1% more yield, between 1000 an 1500ppfd. After which it fell off towards 2000, and they had been to 2500. They settled on 1800umol, and 1200ppm of co2. To achieve these levels, they were using R4 lighting. With R6 they got some bleaching and a 17% yield drop.

I have seen this about the R4 before, but what strikes me, is blue and green are presumably getting the other 60%. While other studies are shying away from blue at these levels, and below.

This grower is of course on the fringe of reality, but it's interesting.

 

[greyfader]

Have you done an 8/16 cycle before and seen that rapid increase in ripening rate? Ive heard that the extra dark hours do increase ripening but i heard it was minimal.

You mentioned before you had plants where the terminal colas were smaller than budsites below. What was your ppfd at the time and how close were your fixtures? Ive seen that issue with HPS in the past when my lights were too close. Havent experienced that with leds at all though.

yes, ive done 3 grows using 8/16. the flower pics i put up in the led thread were all from 8/16 grows except for the mayberry bluestar s1, i used 12/12 on it.

the effect is noticeable by maybe 5-10% relative to the induction speed of 12/12.

the ppfd of the high dli grows was about 1500 umols for 12 hours producing 63.8 moles but there is more to the story.

i had two almost identical cuttings from the same donor in the mayberry test grow. one was under 72 bulbs for 1008 watts and the other was 1680 watts with 120 bulbs.

using the par meter, adjusting the lights to where they were producing a 1500 umols spot reading at the top center of the plant.

the plant under the 1680-watt light stunted in veg and developed a far more "busy" interior than the other plant. i had to do a lot more thinning when i went to flower and got a reduced yield compared to the 1008-watt plant.

so it's not just the instantaneous flow rate, it's also the total light applied. the 1680-watt light produced 1500 umols at 30" and still produced 1000 umols 10" below that.

the bulbs in the 72 position light were on centers 5" in one direction and 6" in the other direction.

this light would not quite produce 1500 umols because of this spacing. as i lowered the light the beam overlap was not close enough. but it does produce 1200 in the center at about 12".

the 1680-watt light has bulbs on 4" centers and it is too close.

i'm thinking a 5x5" spacing with these 14-watt bulbs would be ideal.

i think that, with leds, we are illuminating more photosynthetic surface area than a hid light of the same electrical consumption.

i've been using jack's 5-12-26 with calcinit since march of 2010. under hps i never had to add magnesium as the base formula has 6.36% in it already. with leds i now have to use the 3-2-1 formula, which should be written 3-1-2 as that is the proper mixing order.

per gallon it's 3 gr jacks, 1 gram additional magnesium via mag sulfate, and 2 grams calcinit. i think this is evidence of an increased photosynthetic rate due to leds more complete spectrum and the multi-point nature of the lights hitting a greater surface area than a single-point source. reducing shading.

 

[Corpselover Fat]

I think DLI indoors and outdoors is a different thing for the plant, the sun doesn't loose strength with a meter distance, so it stands to reason an outdoor plant in a sunny day gets way more Carbon. I mean there are these sunny cloudless days were the sun is up for 15h or so.

This is just my speculation, but: One difference between outdoors and indoors is air movement. Even one m/s changes every cubic meter in a second. It's hard to match that indoors and the outside plants thus have access to fresh co2 all the time. While the ambient co2 level indoors might be fine the leaves will form tiny micro climates around them which should be higher in oxygen, and could result in more wasted cycles in photosynthesis. I don't know if that is actually significant, but it is something to consider, imo.

 

[Cerathule]

This was tested and it was directly related to far red. Plants at the same intensity of 1000ppfd under 70+% blue had NO photobleaching vs the lights with more far red had tons. Both leds. Intensity is not what is causing the bleaching according to that study at USU.

What study do you refer to?

 

[Cerathule]

it would be relatively easy to use 8 on, 12 off as your entire day. this would cut 17.66% off the total flowering time. so, with a 9-week strain, you have 63 days at 12/12 but 8/12 would be 11.1258 days off that
and should finish in 51.87 days.

a cheap Nearpow timer from Amazon has a repeat cycle function and you could set that to control lights rather than use a more expensive totally programmable timer.

it is limited to 15 amps @ 120v but you can use a dtdp relay from automation direct to use the timer to switch a bunch of 240v lights. the relays are 40 amp rated up to 600v.

but i think i'm seeing a stronger or more aggressively flowering plant using 8/16. also, i think it enhances terps or at least preserves them better than a 12-hour dark period.

about the mid-day sun intensity i have taken my meter outdoors in the deep south on a clear summer day and it will peg the meter which only goes up to 2000 umols.

I tested something similar to this (16/12) with Cannabis and it doesn't work. You need to have 24h a day - the influence from the ZTL clock genes are too strong.

 

[Cerathule]

This is just my speculation, but: One difference between outdoors and indoors is air movement. Even one m/s changes every cubic meter in a second. It's hard to match that indoors and the outside plants thus have access to fresh co2 all the time. While the ambient co2 level indoors might be fine the leaves will form tiny micro climates around them which should be higher in oxygen, and could result in more wasted cycles in photosynthesis. I don't know if that is actually significant, but it is something to consider, imo.

The indoor ventilation is fine IMO, otherwise studies would have already found this. CO2 moves by diffusion through air, too -ie. along a concentration gradient. IMO too much windspeed is actually not so much helpful because it causes the leaf boundary layer to get reduces which then increases water loss (decreases WUE) and many plants now react to this by closing their stomatas in order to reduce the water loss. They rather get less CO2 than to loose much water - because drought can totally hamper and even kill a plant, while CO2 is anyday available. Many plants, including Cannabis, do even grow special "hairs" (actually these are leaves - trichomes) around the stomatas to reduce windspeed there, increase the leaf boundary layer and keep the rH around the site where the gas exchange happens - high. So what is optimal is to have no standing pockets of air but also no leaves directly blown at by windsheer. Even leaves moving in the wind will encounter a reduction in their photosynthesisrate as it's like a flicker in the systems stoichiometry. Which outdoors, usually doesn't matter as photosynthates are splendid and a sunplant usually had enough light influx even before the diurnal midday depression.

I'm having a hard time thinking about how FRL causes photobleaching. Imagine how much FRL is in sunlight, we're talking 500 PPFD. Photons that are heavily reflected and also transmitted from or through a leaf. The energy doesn't stay as much as in comparison to PAR. Then, when it stays, absorbed by a darkred chlorophyll in PSI, it already reduced the latent heat within the system by the inclusion of phononic energy that is a mandatory requirement for this absorption to happen in the first place. Thus, many studies have shown a photoprotective effect for FRL on chloroplasts.

 

[greyfader]

I tested something similar to this (16/12) with Cannabis and it doesn't work. You need to have 24h a day - the influence from the ZTL clock genes are too strong.

yep, everything on the planet has been entrained into the 24-hour diurnal cycle. that's why i decided not to mess with it.