exoticrobotic
Well-known member
I'm gonna try a Mars planetary 25hr cycle next time. 12hrs light 13hrs darkness.
cmh and/or hps obvs.
cmh and/or hps obvs.
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CMH vs LED vs HPS
- Thread starter Gerardbutler79
- Start date
This is old and has been researched further. The USU course went into way further detail but this at least gives you some info.
Another source
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Cerathule
Well-known member
Bugbee is clearly refering to "RED" light which is NOT
FAR RED light.
And he also states (several times) that this is caused by a "HIGH light" scenario ("600 PPFD" of monochrome red) which actually confirms my initial point about it being tight to the flux. Given the proper amount you can bleach any foliage to dust with light, and if you arrange the photons to form a laser need even way little less energy to cause photodissociation
I studied this for years and know about the inner mechanisms of what happens within the light-harvesting complexes once the excitation surplus energy cannot be further dissipated by non-photochemical quenching (<-- this is strongly correlated with locale heat, JFYI as one doubted the temperature aspects which is ridiculous to begin with if one understands how heat is energy and that can also lead to the buildup of dangerous reactive oxygen species) or Chl-A fluorescence
which is one of the reasons why RED light bleaches most strong. RED causes way less fluorescence than blueshifted wavelengths because fluorescence requires additional energy to happen, that is not given with red wavelengths, but yellow, orange already has it (one big bonus of the HPS spec vs the excessive 660nm of some modern LEDs).
It also is absorbed most strong:
Can far-red light improve plant growth?
The importance of PS I chlorophyll red forms in light-harvesting by leaves
Photoprotection of PSI by Far-Red Light Against the Fluctuating Light-Induced Photoinhibition in Arabidopsis thaliana and Field-Grown Plants
The Origin of the Low-Energy Form of Photosystem I Light-Harvesting Complex Lhca4: Mixing of the Lowest Exciton with a Charge-Transfer State
This is a mistake on my end. It is primarily red light causing the issue. Not FR. I do think they referenced both in the course as a cause. Unfortunately the advanced usu course ended on the 31st and they take away all the modules or id screenshot it. But you are right, its more about Red and not FR. Thats 100 my bad.
Corpselover Fat
Active member
My point was exactly that outside you don't need strong wind to have a lot of air exhange. Little air movement will be very effective. Personally I don't use fans to blow on the plants. I only use the extraction fan to change the air in the tent.
My reasoning for thinking air exchange might be a factor is that adding CO2 indoors allows the plants to grow more and to tolerate higher light levels. I assume that is because of less wasted cycles in photosynthesis.
greyfader
Well-known member
i run my fans by bouncing the air off the walls, not directly at the plants. i want to look at the canopy and see every leaf in the room moving ever so slightly, almost vibrating.
Corpselover Fat
Active member
The biggest reason I never used the fans is noise. Yes, I know there pretty quiet ones these days, but back when I started most around here just used table top fans and I decided not to. Things worked fine without the fans so I never added them in. My grows have always been small and that may be a factor. I use a 120*60cm tent and I've even grown in slightly smaller areas.
I'm gonna try a Mars planetary 25hr cycle next time. 12hrs light 13hrs darkness.
cmh and/or hps obvs.
Ive never seen that.. will be interesting..
Ca++
Well-known member
Most are still using them now. Perhaps with a pole clip or floor stand, but still the same tech. The second place choice is the case fan, found in PC world. 12vdc bldc fans, with a real interest in low noise. Then came the USB fan. Again it's bldc, but with price before performance, where blade designs are concerned. It's just now that AC Infinity have released a clip fan of typical 7" proportions, that uses an EC motor (that's basically bldc, but runs on AC)
While what you have works, you might still want to look at a couple of small fans to get a swirl going. Not a full on tornado, but enough to see some more air exchange at the stomata. I'm not talking outdoor levels of fresh air supply, or enhanced transpiration like a hot lighting source provides. Just a little, to move on depleted air over time. A couple of 8cm things perhaps. Though it may have little value if your have a wall to wall canopy, and air in below it. Giving a steady updraft with your extraction.
Cerathule
Well-known member
Personally I use a number of little rather slowly fans below the canopy - ie. directly above the pots where leaves get lollipopped in flower, and slightly above the tops, mostly to reduce water condensation at budsites later in flower.
You are correct the availability of internal CO2 to the photosynthetic acceptors are one of the most dominant factors of photosynthesis rates with even the spectrum effects of light on stomatal conductance also superceding what's actually happening in the LHCs or the ETC.
I'd say indoors everything can be optimized/ optimal except for the intracanopy photon flux that is better outside.
greyfader
Well-known member
by "intracanopy photon flux that is better outside." do you mean light fleck?
Cerathule
Well-known member
I mean amount of light particles that is deep within the canopy. Outside you have much more ambient diffuse light and also no depreciation with distance
OpenPollenSeeds
Active member
you cant tell me a single lightsource is gonna be better than the 1000s of diodes spread all around. Maybe as supplemental greenhouse lights , but in a home setup ; hell no .
Under cmh 1 plant 1 light might be okay also , but when i grew 4 plants under a cmh i'd only get big buds on the buds towards to middle .
With bar type LEDs my plants grow way more even canopy , bushier , and medium to large buds all over the place .
Under cmh 1 plant 1 light might be okay also , but when i grew 4 plants under a cmh i'd only get big buds on the buds towards to middle .
With bar type LEDs my plants grow way more even canopy , bushier , and medium to large buds all over the place .
Cerathule
Well-known member
Does anyone know the attached study?
I find it interesting that the diffuse light is scattered away slightly more than collimated light. I know there are empirical studies done on plant dry harvest mass that have shown that diffuse light, as in coming from many sources such as LED bar lights, quantumboards etc are going to increase yield (in tomato e.g.) as in comparison to a HID bulb. But then there are also LED lamp producers that narrow down the fixtures beam angle from (usually) 120° to maybe 90° as a means to further "concentrate" the flow of photons directed at the plants leaves. We know that Cannabis is going to change its leaves into the direction of the highest flux in order to maximize light interception.
Also Cannabis has a typical C3 plant leaf architecture:
One of the major differences is the presence of palisade & spongy mesophyll cell tissue in C3 plants. In the palisade cells, the chloroplasts can move around, either to the side to reduce photon capture (in a high light environment, or vice versa) while the deeper penetrating colors green 550nm and farred 730nm are important to deliver photons to the spongy mesophyll chloroplasts.
Thus, C3 has some control over how much ight it can encapture and these plants will even respond to the amount of red vs farred (also blue) in how thin/thick/large a leaf is going to be built in response to the outside spectrum in times when the leaf is still very young/small.
just some food for thought... I'm not sure if there are studies done already on PS rates/ carbon fixation/ dry harvest mass with LED bar light at differetn beam angles....
I find it interesting that the diffuse light is scattered away slightly more than collimated light. I know there are empirical studies done on plant dry harvest mass that have shown that diffuse light, as in coming from many sources such as LED bar lights, quantumboards etc are going to increase yield (in tomato e.g.) as in comparison to a HID bulb. But then there are also LED lamp producers that narrow down the fixtures beam angle from (usually) 120° to maybe 90° as a means to further "concentrate" the flow of photons directed at the plants leaves. We know that Cannabis is going to change its leaves into the direction of the highest flux in order to maximize light interception.
Also Cannabis has a typical C3 plant leaf architecture:
One of the major differences is the presence of palisade & spongy mesophyll cell tissue in C3 plants. In the palisade cells, the chloroplasts can move around, either to the side to reduce photon capture (in a high light environment, or vice versa) while the deeper penetrating colors green 550nm and farred 730nm are important to deliver photons to the spongy mesophyll chloroplasts.
Thus, C3 has some control over how much ight it can encapture and these plants will even respond to the amount of red vs farred (also blue) in how thin/thick/large a leaf is going to be built in response to the outside spectrum in times when the leaf is still very young/small.
just some food for thought... I'm not sure if there are studies done already on PS rates/ carbon fixation/ dry harvest mass with LED bar light at differetn beam angles....
radioman
Active member
Seems like now - all the cannabis at the Shop is grown under LED's (unless outside). I bought some a few days ago here in Vermont & the grower's website brags about the "State of the Art Facility". It is good weed. So if a person is going to buy commercial weed - it's going to be "Clone Weed" hydroponically grown, under LED lights...
I'm using LED's now too. I think for my vegetables and "starter plants" - I actually still like my old basic Hydrofarm Metal Halide for the first month. I just put a whole bunch of LED "started" plants out but I still like the old light. Except for the heat and electric bill...
I'm using LED's now too. I think for my vegetables and "starter plants" - I actually still like my old basic Hydrofarm Metal Halide for the first month. I just put a whole bunch of LED "started" plants out but I still like the old light. Except for the heat and electric bill...
Watch me.
Brother Nature
Well-known member
I'm noticing slight differences in my Sour Diesel in the cmh/led vs. led only run. CMH is top photo, LED is bottom. The cmh/led grow is my second run with her though so technically I should be growing her better regardless of light source, but it'll be interesting to compare the two. Photos definitly take better in LED rooms.
Ca++
Well-known member
You probably shouldn't read this.
25% more yield with a diffused LED ?
First, this is what I mean by diffused led: From here: There are studies online that diffused light is better compared to ones without... I am no expert, but would love to hear from others whether they benefitted from diffusing lights, especially LED´s. I have noticed that plants...
www.icmag.com
Ca++
Well-known member
It would be interesting to look at the leaves grown under different lights.
As a rough guide, we know indoor plants moved outdoor, will often bleach. I think I see this a lot less now I use LED not HPS. Though it's not really the blue levels that get the attention in this talk, it's the UV. Anything damaging, leads to protection mechanisms. Thicker leaves in general, that are a little less effective. While leaves grown under sodium, are likely the thinnest. Good at light capture, but easier to damage.
As I say, a study would be nice.
What I'm really thinking about, is how growing under LED might not be the best idea, if you flower under HPS. I have not done it far a while, but do recall a rather different look to the vegetation grown after the light change. You could see the old and new.
I'm also looking at peoples moves to LED and some of the instant leaf issues they saw. Where these leaves just not made for LED lighting. Lighting which was also a lot brighter in many cases. The downturn was often in 24 hours, and we still see such posts today.
I see them mid leaf stripes still, if I increase light 10% every day, for a few days. The new leaves grow fine, and it's just a few of the upper middle ones that do it. So overall I ignore it, but it is still present. Older leaves that won't take it, while the new ones do. So I have to presume, they grew with certain expectations.
As a rough guide, we know indoor plants moved outdoor, will often bleach. I think I see this a lot less now I use LED not HPS. Though it's not really the blue levels that get the attention in this talk, it's the UV. Anything damaging, leads to protection mechanisms. Thicker leaves in general, that are a little less effective. While leaves grown under sodium, are likely the thinnest. Good at light capture, but easier to damage.
As I say, a study would be nice.
What I'm really thinking about, is how growing under LED might not be the best idea, if you flower under HPS. I have not done it far a while, but do recall a rather different look to the vegetation grown after the light change. You could see the old and new.
I'm also looking at peoples moves to LED and some of the instant leaf issues they saw. Where these leaves just not made for LED lighting. Lighting which was also a lot brighter in many cases. The downturn was often in 24 hours, and we still see such posts today.
I see them mid leaf stripes still, if I increase light 10% every day, for a few days. The new leaves grow fine, and it's just a few of the upper middle ones that do it. So overall I ignore it, but it is still present. Older leaves that won't take it, while the new ones do. So I have to presume, they grew with certain expectations.
exoticrobotic
Well-known member
Led seems to create the thickest stubbiest leaves with cmh leaves slightly thicker but still not stubby and then leaves under hps are paper thin, like you said somewhat delicate but still nice and long.
If i wasn't planning a haze grow in the next couple of months and wanted the extra terps that cmh gives i'd go back to using only hps.
I much prefer the consistency of hps flowers, vs cmh or leds, less stems less stalks.
I also prefer the bassier buzz of hps flowers.
If i wasn't planning a haze grow in the next couple of months and wanted the extra terps that cmh gives i'd go back to using only hps.
I much prefer the consistency of hps flowers, vs cmh or leds, less stems less stalks.
I also prefer the bassier buzz of hps flowers.
