wietefras
Well-Known Member
There really is no "they want more" plants adjust to the light intensity you give them.
DLI can be anywhere in a huge range and the plants will be fine with all of it.
Cannabis Daily Light Integral
- Thread starter cdgmoney250
- Start date
DLI can be anywhere in a huge range and the plants will be fine with all of it.
vintagedvd
Active Member
Well... the 3rd COB didn't made the leaves droop at all (150W at 40cm distance). Tomorrow I'll try the 4th and final COB. I'm very curios about that. I think there could be many variables involved. Like trying to catch up from the period that it didn't had enough light, or the strain, which is a light hungry strain SSH. But she's fairly small, the 2 new tops have 2cm in length (1inch), and this makes things confusing.
I'll let you know how things go tomorrow. I'll post a picture too.
@wietefras
I understand that, I just wanted to see if my lights can reach the maximum DLI of the current plant, knowing the leaves will droop in the part of the "day" that they do.
I'll let you know how things go tomorrow. I'll post a picture too.
@wietefras
I understand that, I just wanted to see if my lights can reach the maximum DLI of the current plant, knowing the leaves will droop in the part of the "day" that they do.
ttystikk
Well-Known Member
Rahz
Well-Known Member
Which spectrum is more desirable ultimately comes down to two factors quality and quanity, but beyond that Yoda has an interesting point. There's no test evidence one way or the other to show (that I know of) whether ambient heat is a reasonable analog to directional or somewhat directional radiant heat. It's reasonable to suspect plants are optimized for a certain degree of both ambient heat and solar IR.
It's been documented enough IMO to suggest that spectrum plays a small part in the equation but when considering the efficiency gains -vs- yield gains, is it hampered to some degree by a loss of directional IR? I don't know.
If there was something to it, it could be possible to improve yield density with some full spectrum IR added, but additional energy use could negate any possible benefit in terms of yield per watt. If this is all true then HPS bulbs do provide free IR. Turning up the ambient temperature might offset this effect to some degree, but it's not a direct analog.
Take with a grain of salt. Beyond GPW there is GPParW. It's rare to see HPS growers hitting +1.5 GPW and LEDers getting ever closer to 2. That's efficiency. When yield is broken down further, compared to only the PAR emission, the impressive results with both types of light might be about 3.5, even 4 GPPW in some cases with peeps who know their shit. More common results using both types of light will be in the 2-3 GPPW range. This is based on various anecdotal postings I've read over the years and isn't well tested science, but I don't get the idea a PAR watt's worth of HPS light vs a PAR watts worth of LED light are much different in terms of yield and quality.
LED DIYers today should be looking at 55-65% efficiency at the cob/board/strip and using 1/3 to almost 1/2 less wattage for the same results. An additional benefit if that's not attractive enough is the expectation of years without any part cost or labor and almost no intensity loss across the same period.
Over the next few years I predict we'll see the decline of the bulb in all applications. It will be difficult to argue HPS is better when nobody is using it anymore.
It's been documented enough IMO to suggest that spectrum plays a small part in the equation but when considering the efficiency gains -vs- yield gains, is it hampered to some degree by a loss of directional IR? I don't know.
If there was something to it, it could be possible to improve yield density with some full spectrum IR added, but additional energy use could negate any possible benefit in terms of yield per watt. If this is all true then HPS bulbs do provide free IR. Turning up the ambient temperature might offset this effect to some degree, but it's not a direct analog.
Take with a grain of salt. Beyond GPW there is GPParW. It's rare to see HPS growers hitting +1.5 GPW and LEDers getting ever closer to 2. That's efficiency. When yield is broken down further, compared to only the PAR emission, the impressive results with both types of light might be about 3.5, even 4 GPPW in some cases with peeps who know their shit. More common results using both types of light will be in the 2-3 GPPW range. This is based on various anecdotal postings I've read over the years and isn't well tested science, but I don't get the idea a PAR watt's worth of HPS light vs a PAR watts worth of LED light are much different in terms of yield and quality.
LED DIYers today should be looking at 55-65% efficiency at the cob/board/strip and using 1/3 to almost 1/2 less wattage for the same results. An additional benefit if that's not attractive enough is the expectation of years without any part cost or labor and almost no intensity loss across the same period.
Over the next few years I predict we'll see the decline of the bulb in all applications. It will be difficult to argue HPS is better when nobody is using it anymore.
ttystikk
Well-Known Member
HID lights do NOT provide 'free' IR; you're definitely paying for it.
My hypothesis is that plants need heat for transpiration, therefore they don't necessarily care whether it's ambient or IR as long as it supports that goal.
I agree with you that the switch from HID to LED is well underway. The only doubters left are those who haven't made the necessary adjustments to growing style and environment.
wietefras
Well-Known Member
I actually got pretty similar results in g/PAR W with HPS and leds. Slightly higher with HPS possibly.
There was a research paper that came by a few weeks ago which illustrated that when plants were grown under HPS and led (using the same average PPFD), that the HPS side produced a bit more yield. Yet with lower THC concentrations.
Yodaweed
Well-Known Member
In my opinion heat and IR spectrum has a direct correlation to plant metabolism , it's why you need to heat your grow area with LEDs to gain the same metabolic rate hps plants have.
Also most plants are bred either outdoors or under hps and have been for many years, I believe this is another reason why you can see so many metabolic problems under LEDs.
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ANC
Well-Known Member
Temp control is "simply" a matter of scaling the grow to the size of the room (within reason). A room packed end to end is going to need cooling on HPS or LED, simple extractive venting is likely not going to keep up over the peak of the day in summer..
The within reason qualifier above has to do with geography. The more your conditions vary from summer to winter and further away it is from being 28C all day long the more external input you will need to keep parameters in check. Like I said before, there are no tropical fish farms in Alaska for a reason.
The within reason qualifier above has to do with geography. The more your conditions vary from summer to winter and further away it is from being 28C all day long the more external input you will need to keep parameters in check. Like I said before, there are no tropical fish farms in Alaska for a reason.
Randomblame
Well-Known Member
Look at this journal, bro!
He tried to use as much light as possible using 8 QBv2 and he also added 1500ppm CO2 to max out light usage. More than 1050μMol/s/m² for 12h was impossible without harming the plants. Most info are in the first 10 pages and the whole thread has 28 pages or so currently.
https://www.rollitup.org/p/14607471/
He tried to use as much light as possible using 8 QBv2 and he also added 1500ppm CO2 to max out light usage. More than 1050μMol/s/m² for 12h was impossible without harming the plants. Most info are in the first 10 pages and the whole thread has 28 pages or so currently.
https://www.rollitup.org/p/14607471/
caretak3r
Well-Known Member
thanks! I'll review it. I'm wondering what happens when I push 2000+ uMol/s/m2 for 1 hr or 2hr... theoretically MJ should take 2000 uMol if the sun dishes that much out. Where is the top end is what I'm wondering.