Lighting Quantum board thread.
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I have contacted a few of them on there n they all get back to me about a normal led light n say they dont carry what im asking about lol when it shows the pic of it...that site is kinda weird and confusing to me lol
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Has anyone looked at the PPFD numbers on the quantum boards and plugged them into the DLI equation? Something doesn’t quite add up. According to the charts and numbers, I should be fine running my light at full power 18” from the top of the canopy 24 hours a day. However, I can’t even run it at full power 30”+ from the top of the canopy for 18 hours per day. Any clues why? I know a reflective interior on my tent can add 10% to 20%, but if the PPFD readings are taken in a reflective tent, isn’t that accounted for in the PPFD readings? I should still be safe adding 20% and yet, I’m not. I’m seeing all kinds of light-stress-related issues.
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- ALL AUTOS BABY and some photos
Iam getting leaf stress to I raised them as high as I could They are doing great Imo But I have quite a few normal cobs and older led lights hanginging a little lower but not much I think I am at maxiumum light for my space.
what drive current are your boards at @mcpd_refugee ?
am I right in understating you that you get light stress at 18" ?
Don't run them at Max. You should drop by my current grow i linked a couple posts ago. I learnt it the hard way.
I used COBs last grow and they are very different with QBs imho. I seem to be able to get COBs closer but its weird cos aren't COBs more powerful, especially at the center?
Anyways, i read on another forum that for seedlings, its no more than 30%. I forgot the numbers for veg and flower but I bet you can adjust easily from after seedling stage. Even then, i tried to push my luck with 50++% and got burned bad. I had to lower it to below 30% at about 15-18 inches or so to hit a sweet spot.
Even at Day 21 today, they are still getting about 30%++ which is 120W out of a possible 350W. One girl still seems to canoe a bit but she growing good so gonna leave it.
Conclusion: These lights are powerful so becareful with them.
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Don't run them at Max. You should drop by my current grow i linked a couple posts ago. I learnt it the hard way.
I used COBs last grow and they are very different with QBs imho. I seem to be able to get COBs closer but its weird cos aren't COBs more powerful, especially at the center?
Anyways, i read on another forum that for seedlings, its no more than 30%. I forgot the numbers for veg and flower but I bet you can adjust easily from after seedling stage. Even then, i tried to push my luck with 50++% and got burned bad. I had to lower it to below 30% at about 15-18 inches or so to hit a sweet spot.
Even at Day 21 today, they are still getting about 30%++ which is 120W out of a possible 350W. One girl still seems to canoe a bit but she growing good so gonna leave it.
Conclusion: These lights are powerful so becareful with them.
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I'm guessing this could be an Auto thing. They do like a little less light than a photo. I've not done an Auto under my QB's yet but I did find that most Auto strains under my cobs liked to get no closer than 18-15" before they started to show light stress.
I’m going to try to be a little more clear. Some times I’m not very good at that. I apologize.
I have a 135 watt Quantum Board 288 V1 in 4000K. It came with the Meanwell HLG-120H-54A LED driver. That driver has two adjustment pots on it that allow you to adjust the voltage and current. I am growing in a 2’x2.5’x7’ Gorilla Grow Tent.
HLG links to a bunch of information put out by a guy named LEDGardener. There are a bunch of PAR charts that he’s compiled on various HLG lights in his reviews. For the 135w QB 288 V1, at 18”, he measured the PPFD for the light as 710 µMol/m2/S using an expensive PAR meter with the light running at full power. His measurements were taken in a 2’ x 2’ Reflective tent. LEDGardener’s PPFD reading for the light at 12” is 1140 µMol/m2/S. I have read that the ideal PPFD for cannabis is around 1500.
Daily light integral (DLI) is the amount of PAR received each day as a function of light intensity (instantaneous light: μmol. m-2. s-1) and duration (day). It is expressed as moles of light (mol) per square meter (m-2) per day (d-1), or: mol. I have read that the ideal DLI for cannabis is around 65.
The equation you use to determine the DLI for your given lighting schedule is: 60 seconds x 60 minutes x # of hours your light is on x (PPFD/1,000,000). If your light is on an 18/6 schedule, the formula becomes: 60x60x18x(710/1,000,000). The result of that equation is 46.008. So, according to all the maths, one should be able to run the light in a 2’x2’ reflective tent 18” from the top of the canopy 18 hours a day and still be under the ideal amount of light for your plants. You could even run them 24 hours a day and still only get a DLI of 61.344, which should be almost ideal. Right?
However, this is not what I have found in my experience. I was running my light at 30” from the top of my canopy 18 hours a day at full power and I was seeing symptoms of what I later found out was light stress. My plants leaves were showing deficiency and toxicity for different nutrients at the same time. I was trying to adjust the nutrients thinking that my light was well within the safe parameters of operation. In fact, I thought that I wasn’t giving my plants enough light. Right now, I still have my light at 30” from the top of the canopy and I have the voltage pot dimmer turned all the way down. I’m starting to see some healthy growth.
So, my thinking on this is that either 1.) the maths are wrong or 2.) the PPFD readings are wrong or 3.) there’s something about the Quantum Board lights and autoflowers that don’t fit the maths and the readings (this would be something like autoflowers need less light than photoperiods or there is some additive effect of the spacing of the LED chips on the boards or something else that I cannot think of at the moment). What really irks me at the moment is that I have no really accurate gauge of how much light my plants are getting because there are no readouts for the pot dimmers and I cannot afford a PAR meter. And even if I COULD afford a PAR meter, it doesn’t seem to give an accurate indication of what is happening at the canopy-level with these lights.
Or...am I missing something here? Does this even make sense?
I have a 135 watt Quantum Board 288 V1 in 4000K. It came with the Meanwell HLG-120H-54A LED driver. That driver has two adjustment pots on it that allow you to adjust the voltage and current. I am growing in a 2’x2.5’x7’ Gorilla Grow Tent.
HLG links to a bunch of information put out by a guy named LEDGardener. There are a bunch of PAR charts that he’s compiled on various HLG lights in his reviews. For the 135w QB 288 V1, at 18”, he measured the PPFD for the light as 710 µMol/m2/S using an expensive PAR meter with the light running at full power. His measurements were taken in a 2’ x 2’ Reflective tent. LEDGardener’s PPFD reading for the light at 12” is 1140 µMol/m2/S. I have read that the ideal PPFD for cannabis is around 1500.
Daily light integral (DLI) is the amount of PAR received each day as a function of light intensity (instantaneous light: μmol. m-2. s-1) and duration (day). It is expressed as moles of light (mol) per square meter (m-2) per day (d-1), or: mol. I have read that the ideal DLI for cannabis is around 65.
The equation you use to determine the DLI for your given lighting schedule is: 60 seconds x 60 minutes x # of hours your light is on x (PPFD/1,000,000). If your light is on an 18/6 schedule, the formula becomes: 60x60x18x(710/1,000,000). The result of that equation is 46.008. So, according to all the maths, one should be able to run the light in a 2’x2’ reflective tent 18” from the top of the canopy 18 hours a day and still be under the ideal amount of light for your plants. You could even run them 24 hours a day and still only get a DLI of 61.344, which should be almost ideal. Right?
However, this is not what I have found in my experience. I was running my light at 30” from the top of my canopy 18 hours a day at full power and I was seeing symptoms of what I later found out was light stress. My plants leaves were showing deficiency and toxicity for different nutrients at the same time. I was trying to adjust the nutrients thinking that my light was well within the safe parameters of operation. In fact, I thought that I wasn’t giving my plants enough light. Right now, I still have my light at 30” from the top of the canopy and I have the voltage pot dimmer turned all the way down. I’m starting to see some healthy growth.
So, my thinking on this is that either 1.) the maths are wrong or 2.) the PPFD readings are wrong or 3.) there’s something about the Quantum Board lights and autoflowers that don’t fit the maths and the readings (this would be something like autoflowers need less light than photoperiods or there is some additive effect of the spacing of the LED chips on the boards or something else that I cannot think of at the moment). What really irks me at the moment is that I have no really accurate gauge of how much light my plants are getting because there are no readouts for the pot dimmers and I cannot afford a PAR meter. And even if I COULD afford a PAR meter, it doesn’t seem to give an accurate indication of what is happening at the canopy-level with these lights.
Or...am I missing something here? Does this even make sense?
Thank you @mcpd_refugee for this post, i will be re-reading this over and over...
When it comes to to LED's I'm a trial and error kinda guy. I think I get what your saying and the more i read it it makes more sense but is it really more of a rule of thumb to go by? and go with that green finger gut feeling.
Some of those auto's real do need a lot less light and I've seen a massive difference from strain to strain in the same tent over a quite a few grows, even between genotype's. On one grow I did a full tent (6 of each) of GG4 (fastbuds) and G14 (fast buds). The GG4 shied away from the light and I had loads of light issues, cal mag etc. Now the G14 showed now signs of stress and grew to with in 5" from the cobs, lapping the light up like it was going out of fashion. Not one issue with the G14... those observation's are made with citizen 1212's at 3000/3500k, 1400ma and 1050ma.
Different story with my photo periods, not had an issue's yet apart from they get under the light for the first week and they are getting used to it from a T5.
I just remembered something else I read with regards to intense lighting. I think it was an article on High Times or Maximum Yield or some other such place. Anyway, the article said that with intense lights, better result can be achieved with a 6/2 lighting schedule because problems arise when you subject the light to an extended period of intense lighting. The article said that better result could be had by running 6/2 three times per day. I don’t remember off the top of my head whether they cited or mentioned any study for that. Anyone ever try this?
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