Max PPF/PPFD with and without Co2
- Thread starter Smoke-A-Cola
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Yeh, that's a good video - "required reading"!
I realize that this is an older message but, since you're still on board…
HLG is a tough one because they're a board light and they have significant hotspots. My hunch is that commercial growers are OK with that because of how their grow environment is set up but folks who haven't seen the PPFD maps don't realize that there's a rapid roll off in PPFD once you leave the center of the light. HLG recommends high hang heights that are significantly greater than vendors who sell bar lights - check out HLG vs Migro, for example.
"Photone" - as an HLG owner, you're in the catbird seat because HLG publishes conversion factors to convert lux to PPFD for their lights. I've tested Korona and Photone and traded email with their programmer (I've been writing software for a living for > 30 years so he and I have some common ground) and, given the alternatives that are available, I'd go with either a light meter and use the conversion factor from HLG (or use 0.015 and declare victory) or, put the $$ into a quality PAR meter (SpotOn, Li-Cor, or Apogee for a PAR meter and not anything that uses the sensor that Photobio because that sensor highly unreliable and, second, not able to read wavelengths > 660nm).
(Sorry to have to paste in pictures but we can't up load an Excel document.)
and
plumsmooth
Well-Known Member
Can someone address, excuse me if I missed it -- what about the top or side of a plant hitting 1000 Micro Moles but the rest of the plant getting 607 hundred. But then the bottom area only getting < 300 Should I be thinking Collectively here also collectively double that is -- including DLI or whatever that Acronym is ha ha....???
I have big plants and hard to space the light perfectly gets tiring always moving them around....
Here's my Chimera #2. Also will my Photome Light Meter reflect, I mean calculate, the overlapping addition light sources. I figure yes, sort of, but not entirely sure. For Example if I run 2 lights side by side will the two sources double the Light Meter reading? Geez...
Here you can see I have 3 light sources maybe even a little from a 4th CMH hitting this plant. Hter highest Reading is under the HLG 350 only set at like 30 or so %
I guess similar to DLI all the light hitting different parts of the Plant add up to get your overall amount blah blah blah...
I have big plants and hard to space the light perfectly gets tiring always moving them around....
Here's my Chimera #2. Also will my Photome Light Meter reflect, I mean calculate, the overlapping addition light sources. I figure yes, sort of, but not entirely sure. For Example if I run 2 lights side by side will the two sources double the Light Meter reading? Geez...
Here you can see I have 3 light sources maybe even a little from a 4th CMH hitting this plant. Hter highest Reading is under the HLG 350 only set at like 30 or so %
I guess similar to DLI all the light hitting different parts of the Plant add up to get your overall amount blah blah blah...
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First issue - unless you have calibrated Photone, your numbers could be significantly incorrect. I've tested Photone twice and that's one reason why I have a PAR meter. A PAR meter is pricey and I don't know that I would buy one if I were starting over. A Uni-T Bluetooth lux meter is money very well spent. A lux meter is only slightly more inaccurate than a PAR meter and, in practical terms, it's as good as a PAR meter.
The other stuff - welcome to the world of trying to figure out lighting your grow!
Click on one of the links in my sig block and you'll see that I've published my light values as well as how I measure light. If you want to go down that rabbit hole, the trick is to sample light levels at different locations on the canopy to get a "picture" of PPFD at different points of the canopy.
Here's the data for my current grow, only in day 32:
X2=the model of the light
303= the wattge
767 is the PPFD on the left side, 872 is center rear, 801 center mass, 800 front center, and 858 is center right. Average PPFD is 820 and with a photoperiod of 24/0, the DLI is 70.8
As the plant grows, I sample more points. When the plant is in mid to late flower, I may take over 20 samples.
Photons are photons - if you add more lights, you've got more source of photons and, unless you turn your light down, they'll generate more photons. I've used up to three lights on my grow (a 2' x 4' tent) because autos can get pretty rambunctious.
PPFD=photosynthetic photon flux density=how much light is falling on a given area in a given time. It's reported in µmol which is micromols per square meter per second.
DLI=daily light integral=how much light fell on a given area in a given time. It's reported in mol which is the mols falling on a square meter for a 24 hour period. A mole is a furry little animal. A mol is a huge amount of photons.
PPFD="We got 1 inch of rain yesterday. It all fell at 9:02 AM" That's 1" of rain in a day but it all fell in one minute = your garden got flooded out.
DLI="We got 1 inch of rain yesterday. It started raining yesterday morning and rained all day and night" = your garden got a good soaking.
A cannabis leaf will tolerate 800-1000 µmol. Ideally, an entire canopy will get that level of light but most grows do not have a level canopy so you'll see that top of the canopy is, say, 900µmol but the edges and corners may be 700 or 600.
To even out the canopy, we can do high stress and low stress training as well as changing the position and intensity of our lights. For more than one grow, I've taped a sheet of bond paper around the center of my light. That blocks some of the light in the center which allows me to increase the wattage which increases the PPFD around the edges and corners. No issue heat from the light hitting the paper - IIRC, it was a bit over 100° which is well below a temperature where it could be a fire hazard.
plumsmooth
Well-Known Member
Wait a Minute I forgot I was already a part of this Thread oh SHeeeeeet....
plumsmooth
Well-Known Member
I think more often then I have realized I have been over-lighting my Veg Plants. And then thinking I was having Nutrient issues -- which of course I was -- as some of the over lighting issues manifests in nutrient issues! But also and I am still trying to figure out this important parameter. LST as in Leaf Surface Temperature.
I spent a couple of years transitioning to LEDs only literally on the final Week I got rid of my Last Non LED light was when I even discovered the Issue of No or minimal Infrared Heat being generated by LED's hence the need to raise temperature. DUH I was irritated. Luckily I didn't throw away my CMH's!!!
F that. I like being comfortable in the grow room which is not at 85 Degrees! I said screw it and I decided most strains can tolerate a little lower LST however, when the Lights get Turned up and you have the combination of High PPFD but low temperature i.e. maybe <75 Degrees LST maybe then other problems are brewing behind the scenes! Like low temp exacerbates the Too <much light issues???
I have even considered getting those Black No Light Heat Lamps to throw in' but adding a CMH seems smarter.
I wish I had 150 CMH's to spot light in-between my LED's.
Is any manufacturer making LED panels with intermittent Infrared Bulbs on the board or panels?
? I bet 'they' don't make an LED Infrared Bulb so it would have to be something completely different...
I spent a couple of years transitioning to LEDs only literally on the final Week I got rid of my Last Non LED light was when I even discovered the Issue of No or minimal Infrared Heat being generated by LED's hence the need to raise temperature. DUH I was irritated. Luckily I didn't throw away my CMH's!!!
F that. I like being comfortable in the grow room which is not at 85 Degrees! I said screw it and I decided most strains can tolerate a little lower LST however, when the Lights get Turned up and you have the combination of High PPFD but low temperature i.e. maybe <75 Degrees LST maybe then other problems are brewing behind the scenes! Like low temp exacerbates the Too <much light issues???
I have even considered getting those Black No Light Heat Lamps to throw in' but adding a CMH seems smarter.
I wish I had 150 CMH's to spot light in-between my LED's.
Is any manufacturer making LED panels with intermittent Infrared Bulbs on the board or panels?
? I bet 'they' don't make an LED Infrared Bulb so it would have to be something completely different...
plumsmooth
Well-Known Member
Right Now I think any more then 1000 non CO2 PPFD hitting a plant is too much in Veg?
It's not likely that a grower can get cannabis to > 1kµmol, on a sustained basis.
In ambient CO2, the light saturation point ("LSP") for cannabis is 800-1000µmols. It's strain dependent and the other parts of the grow environment need to be optimized ("co-optimzed" in Bugbeespeak) to support that.
Here's a graphic…from a Bugbee vid:
If a grower reports that they're getting over 1000µmol, the issue, to me, becomes how it was measured. It's unlikely that cannabis will grow well at light levels that are truly above 1kµmols. I've done 1200+ to try to light a huge plant + a tiny plant (think about the movie "Twins") and the big plant fox tailed. Oops. I got my head out of my ass and spend $100 on a little Vipar XS-1500.
I haven't found any reason to not get my grows to the LSP as soon as I can. The cost difference between, say 600 µmol and 800 or 900 is minimal, even at California electricity prices, and cannabis loves light so let 'er rip.
Week4@inCharge
Well-Known Member
Ive had some good fat buds from 800 to 1000. And if I have problem buds they're are always at or above the 1000 mark, hardly any problems 900 and below. (Don't use CO2) my experience so far. (12-12 flowering light cycle) and yeah....1000 is crazy amount of light for veg.
I don't think this is the case. Plant conduct photosynthesis using light and water. Too much light is met by photo avoidance (tacking/canoeing and rotation of the leaf around the petiole) and then by destruction of leaf tissue if the condition persists.
The primary driver of nutrient uptake is transpiration - plants use water to cool off and they take up that water from the roots zone, along with chemicals (ferts). The primary driver of transpiration is humidity and temperature (which can be expressed as "VPD") and wind plays a secondary role. Growers who switch from gas discharge to LED are growing in a very different set of temperatures because LED do not heat the leaf surface the way a gas discharge light does.
Per above, temperature is one of the factors that drives transpiration and transpiration is what causes water uptake which is what causes nutrient uptake. Cut out all the stuff in the middle and you get temperature driver nutrient uptake.
What does that mean?
If your temperatures are off, the biggest change in nutrient uptake is our friend Calcium. It's only natural to assume/conclude that you might get nutrient problems because you switched to LED's but it ain't the lights. A photon from CMH is the same as a photon from the sun which is the same as a photon from a flaming fart. The key is that the leaf surface temperature ("LST") is a lot lower because the plants aren't getting the IR from the light, so that throws off VPD and that causes/can cause Ca uptake to go sideways.
LST is one of the parameters and, if you're thinking along those lines, I would urge you to wrap your head around VPD because it's so important to a really healthy crop. Sure, many grows don't give a hoot about VPD and there's no problem with that. Cannabis is an amazing plant and you can get a great crop without being able to even spell VPD. On the other hand, if you don't pay attention to VPD, it's not unlikely you're going to have really lousy VPD at some point and your crop will suffer.
85's pretty darn high. My current grow will stay below 80 because I think/suspect that there's a reduction in THC levels when you get into the 80's. That's just from a comment in a video by a former Bugbee student. The issue is that the plant will grow more, that's been demonstrated over and over. The question is the weed better? Dunno.
Yes, LED manufactures are adding IR but that's a price driver and, to some extent, the grow light market is similar to the PC market in the 90's — a race to the bottom for price so you can't do much innovation. I said "to some extent" because there is R&D (the Vipar Spectra XS-1500 Pro kicks a lot of ass!) but, when you look at the products from the popular manufacturers, there's a lot of similarity and that's because they're fighting in well defined price bands.
Once you get outside the pure commodity light (BTW, no insult meant to any of the popular manufacturers), some companies are adding IR and UV but that's not an easy sell because that drives price and I think it's fair to say that adding IR and UV are not proven to add much to the quality or yield of a grow. I'll be the first to admit that I'm not up to the minute on that aspect because I'm not in the market and, when I was looking at UV and IR 6, 8, or 10 months ago, there wasn't a clear cut answer. (If someone has data on that, please provide links.)
If you're keen on trying IR, I use a Royal Blue puck from Rapid LED. They've got a selection of fixtures and piece parts. You might want to check them out.
I wouldn't add IR to increase LST, though. I can't imagine it's cost efficient to go that a route vs just using the heat from the driver, in a small setup, or fiddling with the HVAC in a large grow. Dunno 'cause I grow in a pissant little 2' x 4'.
Hollatchaboy
Well-Known Member
They make both infra red bulb and diode. Remember the TV remotes from the 80s? Infra red bulb.
Night vision camera..... Infrared red diode.
plumsmooth
Well-Known Member
This is the one at the Tops and tips, over and over again, I have problems with, but I notice it more when the light is too strong and the temp is too low.
plumsmooth
Well-Known Member
That's funny and great because I was imagining a Chart like that for an acquaintance that was getting annoyed when I tried to share a lot of Info at once. He got overwhelmed... That's when I realized Cultivation Knowledge isn't learned overnight... And actually it is always evolving. I never read about VPD or Micro Moles when reading Ed Rosethal 30 years ago. Remember Foot Candles?
Cause and effect?
Why do you say that the light it "too strong"? Are you seeing light avoidance or tissue damage/death?
Per above, why do you say "temp is too low"? Cannabis will grow in temps down to the low 70's.
The graphic below is from a paper by "Chandra", showing how net photosynthesis changes at different temperatures for different PPFD's. Check out the temps, 20 and 25° C. The difference between those temperatures, in terms of net photosynthesis, is miniscule.
I would posit that it's not the temperature, rather it's the temperature + RH that throws things off. Are you keeping VPD in range at low temps?
Yeh, it takes a while for it to sink in! I only do two grows a year so I forget a lot of the subtleties.
Agreed - the knowledge base is expanding rapidly as it becomes legal in more states but also because our friends in the Great White North went legal. Guelph is a highly renowned university (I went to college in Canada so I have some familiarity with the schools there) and they're doing a lot of work in cannabis research.
"30 years ago" - you've been in the game for a while, eh? I did one grow in 2017 and then started again in early 2021 so I never did foot candles. From time to time, I use the expression "Before I started growing cannabis, the only thing I grew was old." so there's still lots to learn.
My question - since you were growing well before it was legal, how did you guys stay out of jail?
ttystikk
Well-Known Member
Luck.Yeh, it takes a while for it to sink in! I only do two grows a year so I forget a lot of the subtleties.
Agreed - the knowledge base is expanding rapidly as it becomes legal in more states but also because our friends in the Great White North went legal. Guelph is a highly renowned university (I went to college in Canada so I have some familiarity with the schools there) and they're doing a lot of work in cannabis research.
"30 years ago" - you've been in the game for a while, eh? I did one grow in 2017 and then started again in early 2021 so I never did foot candles. From time to time, I use the expression "Before I started growing cannabis, the only thing I grew was old." so there's still lots to learn.
My question - since you were growing well before it was legal, how did you guys stay out of jail?
Week4@inCharge
Well-Known Member
I know a cop that whenever he found weed on any one he'd somehow lose it in the air. They're human too.
ttystikk
Well-Known Member
Seriously though, strong out of trouble was often just dumb luck - as was being busted by the endless complaints of a neighbor who just flat hated the notion that weed had been legalized in Colorado and he was gonna do whatever he could to ruin my life.
I got the last laugh, though; that turd moved to Wyoming!