HLG 600's and leaf burn

DoubleAtotheRON said:

This was my problem with the top leafs was K lockout from too much N. It's antagonistic with K, and Cal is antagonistic with a lot of other major and micro nutrients. I knew I was N toxic when I noticed my lower leafs were super dark green and shiny. Now that I have cut back on N, It's returned to normal,.. of course those burnt edges are not going to repair, the new growth looks normal and much better.

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Yes, that's what I was thinking also. During flower, the plant will pull K from the nearest leaves to fuel flower formation – which could explain the top growth being affected most, as well as parts of the middle.

The red stems are anthocyanin stress pigments that can be associated with light stress and are not necessariyy phosphorous deficiency but there are grey patches also on some of the leaves that are consistent with phosphorous defciency/lockout.

Overtranspiration not only dries the leaf out, it also draws up a lot of calcium which can antagonise other nutrients – especially K.

I must admit, this one is a bit of a head-scratcher.

What I find strange is that on some "lights out".. I will leave the room and the CO2 is at 1300 when the lights go out. I can come back before lights on, and it still around the same, and other nights, I can come in before lights on and its at 600ish. Temps and RH don't fluctuate that much. 83-86 temps/57-67 RH during lights on.. 77-78 during lights off and about the same RH.

Prawn Connery said:

Yes, that's what I was thinking also. During flower, the plant will pull K from the nearest leaves to fuel flower formation – which could explain the top growth being affected most, as well as parts of the middle.

The red stems are anthocyanin stress pigments that can be associated with light stress and are not necessariyy phosphorous deficiency but there are grey patches also on some of the leaves that are consistent with phosphorous defciency/lockout.

Overtranspiration not only dries the leaf out, it also draws up a lot of calcium which can antagonise other nutrients – especially K.

I must admit, this one is a bit of a head-scratcher.

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Yeah, hard to say without being there. But, I'd say there's a K lockout from something.

DoubleAtotheRON said:

What I find strange is that on some "lights out".. I will leave the room and the CO2 is at 1300 when the lights go out. I can come back before lights on, and it still around the same, and other nights, I can come in before lights on and its at 600ish. Temps and RH don't fluctuate that much. 83-86 temps/57-67 RH during lights on.. 77-78 during lights off and about the same RH.

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How do you reduce humidity? Dehumidifier? No leaks in that sealed room? It would make sense if you were exhausting humdity on some nights and not others. I must admit I don't have a lot of experience with how CO2 systems work, but I do know how plants react.

Prawn Connery said:

How do you reduce humidity? Dehumidifier? No leaks in that sealed room? It would make sense if you were exhausting humdity on some nights and not others. I must admit I don't have a lot of experience with how CO2 systems work, but I do know how plants react.

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Room is sealed up tighter than a frogs ass. Walls are 10 inches thick in a room in side of a room, inside of a building. I have dehuyes pulling around 1.5 gallons per hour during lights on. Lights off.. a bit less. No leaks. I can open the main room door really quick, and it will suck the main door in the entry room closed if I didn't pull it shut all the way. Im in and out of there alot... but not during lights out.

... some of it may be due to how many I have fed that day. Some days I'll have 34 to feed, some days 22, 42, 12, 32... they don't all need feeding at the same time so this may be why im seeing a flux. Feeding 90 currently in week 5. And i'm not the greatest at feeding at the same time everyday. Some days I'll sleep till noon, and then get out there around 2pm to feed, and then other days, I get lazy and wait till 6pm to feed. Lights are out at midnight.

DoubleAtotheRON said:

What I find strange is that on some "lights out".. I will leave the room and the CO2 is at 1300 when the lights go out. I can come back before lights on, and it still around the same, and other nights, I can come in before lights on and its at 600ish. Temps and RH don't fluctuate that much. 83-86 temps/57-67 RH during lights on.. 77-78 during lights off and about the same RH.

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Your CO2 should be increasing at night time. I run mine at 1400ppm and if I don't vent it usually hits 2000-2400ppm by the end of the dark period.

Also my dehumidifier runs harder/more at night. Since your AC won't be pulling the same moisture since it doesn't have the lights reheating the room.

if the door is left open, or gets sucked open which happened in my room before I could see that driving the CO2 down (like to 600, since atmosphere is ~430ppm.)

MidnightSun72 said:

Your CO2 should be increasing at night time. I run mine at 1400ppm and if I don't vent it usually hits 2000-2400ppm by the end of the dark period.

Also my dehumidifier runs harder/more at night. Since your AC won't be pulling the same moisture since it doesn't have the lights reheating the room.

if the door is left open, or gets sucked open which happened in my room before I could see that driving the CO2 down (like to 600, since atmosphere is ~430ppm.)

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Sometimes mine does increase overnight. My AC gets turned up at midnight (lights out) to keep it from getting too cold, so it's not condensating as much at 81 degrees as opposed to 74 during lights on, and there's more heat in the room to convert to condensation. On the door... the main grow is shut tight all the time... I was taking about the entry to the building. I have 2 doors you have to go through to get to the main grow room.

Prawn Connery said:

Yes, that's what I was thinking also. During flower, the plant will pull K from the nearest leaves to fuel flower formation – which could explain the top growth being affected most, as well as parts of the middle.

The red stems are anthocyanin stress pigments that can be associated with light stress and are not necessariyy phosphorous deficiency but there are grey patches also on some of the leaves that are consistent with phosphorous defciency/lockout.

Overtranspiration not only dries the leaf out, it also draws up a lot of calcium which can antagonise other nutrients – especially K.

I must admit, this one is a bit of a head-scratcher.

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A head scratcher indeed. Thanks for the insight though. But ya your right in that it doesn't make sense it's JUST light stress, cause I ran these lights at full power in tents with zero issues. Now this is run #2 in the room where the EXACT same issue is persisting.
So it may not be light stress itself, but something else in the room causing the plants to be extra sensitive to the light.

I'm not sure what else I can change though. As I mentioned CO2 does shut off at night, and is 1500 during the day. Temps and humidity are in check. And I swear my soil is as rich as It could possibly be and I check the ppms and pH, it's all dialed. In the summer when this was happening I brought one of the plants outside and it turned RIGHT around after being out of that room. Likewise I've take plants from my other tents (blurple LEDS) and within a few days they burn the same way.

Side note , my plants in my blurple viodrspectra tents, get the exact same treatment of nectar 4 the gods and compost tea, and I can't get them to grow slow enough, they are just exploding. The treatment is no different, they are in the same basement, same CO2 , temp, humidity. The only difference is they are in a tent, and have blurple viodrspectra above them rather than four HLG 600 quantum boards

Prawn Connery said:

Well I think you might also be on to something with the K lockout as that is generally what a severe K deficiency looks like in flower, but normally it takes a bit longer to get that bad unless something else is contributing or accelerating the deficiency (which is actually a lock-out, not a deficiency).

Actually, I take some of that back as upon closer inspection it's just isolated leaves.

OP, do you spray with anything?

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In veg I preventative spray with azamax, maybe once every two weeks. I've never sprayed in flower

Prawn Connery said:

You can see where the aircon is really having to work over those first two days.

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For sure, those are days the lights were dialed up higher , I've kept turning them down hoping the burning would stop. They have been all the way down for a while now. The ppfd reading at the canopy is back at 200 , which is rediculous. I wanna be running these lights at full power like I used to getting fat sticking nugs. These plants are just so damn sensitive.

Which leads me to another point. This summer I put a bunch of plants out back of the same exact strain. I would water them straight out of the hose most days without Ph'ing or adding nutes just out of laziness and cause it was a fun project. I would still add nutes like once a week. But man they did fantastic, super robust.
S it's so confusing to me why those plants could take anything thrown at them, un-ph'd water , overeatering during rain storms, underwatering on days I wasnt home, yet they were so strong and resilient they finished beautifuly.

Then my HLG plants that I am miticulous about pH, ppm, temp, humidity, water amount , checking run off , are so good damn sensitive the upper leaves burn to a crisp if the light is any closer than 200 ppfd. .

And again I don't think it's nutrient or anything related. Something about the air, light mixture makes way more sense to me. Because it happens to anything I bring into that room. And anything I take out of that room begins healthy new growth and never burns like that again. So it's something in that room.

Starseed.extracts said:

Then my HLG plants that I am miticulous about pH, ppm, temp, humidity, water amount , checking run off , are so good damn sensitive the upper leaves burn to a crisp if the light is any closer than 200 ppfd. .

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they would show these signs at, say, 300 ppfd?!? naaah then it's not caused by the dli ... or maybe ur instrument has trouble catching all the light-rays (e.g. from crosslighting...)
anyway, if something goes astray with certain nutes - imbalance, physiological (internal) deficiency, then chances are some chemo-cycles come to halt or diminish and that could very likely make that plant intolerant to high irradiance... some things in the leaf need to be repaired during the dark period

Kassiopeija said:

they would show these signs at, say, 300 ppfd?!? naaah then it's not caused by the dli ... or maybe ur instrument has trouble catching all the light-rays (e.g. from crosslighting...)
anyway, if something goes astray with certain nutes - imbalance, physiological (internal) deficiency, then chances are some chemo-cycles come to halt or diminish and that could very likely make that plant intolerant to high irradiance... some things in the leaf need to be repaired during the dark period

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Agreed , to to summerize here, there is another factor making them ultra sensitive to the light. That is what I need help with. But as I've mentioned I have tents under blurple viodrspectra LEDs that get the exact same treatment as far as soil and nutes go and I can't get them to slow down, they are growing too quickly and will be larger than I would like by the time they are ready for the flower room. The same goes for every year I do 30 gallon pots of promix outside in the summer. I can feed them whatever and this issue doesn't occur. So it's something in the room. Some odd vpd imbalance or something making the leaves crisp with any normal amount of light.

When I ran these same lights in tents, I would run them at full power and close to the buds, the only issues I would have are light bleaching like the leaves turning like green and the bud tips going totally white like albino weed, but NEVER have had leaves crisp like this. But then again I never ran these lights in an array like this, they were all in separate tents before.

But even healthy plants from my other tent, if I bring them in the HLG room when the lights are turned up at ALL , they do the same thing, then I take that plant out of the room and put it back in the tent and there is zero sign of leaf burn. It makes no sense , driving me crazy.

To summerize again with photos :

First two pics are tent runs of mine with the HLG 600's, turned all the way up. I was pulling over a pound and a half. So I decided fuck it I'll build a room.


Next pic is the first issue I got in the room, you'll see the burned leaves early in veg. Same lights I had in the tent, same everything.

So this started happening early veg. The exact same leaf burn. So I backed the lights way off, and covered the reflective walls

so I turned the lights all the way down, and raised them all the way up and the burning went away completely. They had a nice stretch.

Then day 21 I took down the tapestry so I could get my reflective walls back, and I turned up my lights. According to my apogee meter 800 at the canopy. Which was not even all the way up. And within two days the leaf issue came back 10 fold, plants burned to a crisp. Are still completely stunted. There more borwn leaves than green (I pruned the lowers before any of the burning)

they were getting quite bushy actually
, This is still at 200 ppfd !! It makes zero sense I know.

Now this is TWO days after turning the lights up to 800

just for the sake of references to show I'm not an idiot, these are some of my outdoor girls this year in promix. Same strain I'm having issues with indoors. And these bitches I would water out of the hose half the time! No pH, no nutes sometimes for a week or two weeks.
Also in promix hp.... So what the hell is going on in my room that's making them so damn sensitive is the million dollar question. I will regard anyone who can help me solve this as the "cannabis king" lol

IDK man... still looks like a K deficiency, which if your N toxic, it will lock out the absorption of K. And I think that makes it more light sensitive since it can't move water to the uppers if K deficient. Also can't convert carbs, so that may also make it light sensitive. But the fact that your problem goes away by moving them back into the tent is really weird.