Zinger59
Well-Known Member
you spare no expense, I like your colour scheme. Intensity issue, do the tops bleach out?
HLG 600's and leaf burn
- Thread starter Starseed.extracts
- Start date
Artmann11
Active Member
Huh. Hell if I know. So my quantum boards on my Diablo are different than the R-Spec? Guess I'll have to dig into it before I disassemble it. Lol.I think your confused. Both the Diablo and the R-spec are available in the "Scorpion" configuration
I haven’t done any side by side comparison. But I feel like my plants will handle more light when exposed to UVB.
my dimmers are definitely turned up more then they use to be now that I have a SolarCure bulb.
i use to only use The uvb the last 3-4 weeks of flower. But this run I turned it on at the 12/12 light change.
Plants are super happy. And taking 450-500 watts of cobs in a 3x3 tent.
my dimmers are definitely turned up more then they use to be now that I have a SolarCure bulb.
i use to only use The uvb the last 3-4 weeks of flower. But this run I turned it on at the 12/12 light change.
Plants are super happy. And taking 450-500 watts of cobs in a 3x3 tent.
Prawn Connery
Well-Known Member
That's not light stress. It appears to be heat-stress related. If it were light stress it would be fairly uniform across the top of the canopy. The pistils would be bleached and the top leaves would be fairly evenly yellowed/bronzed – they wouldn't be burned from the tips and edges inwards.
The most obvious clue is some of the lower fan leaves are showing the same symptoms.
A few questions to begin:
Why does your topsoil look so muddy? Are you using diotamaceous earth?
What is your CO2 ppm during lights out? What is it during lights-on? I understand this a completely sealed room?
Do you have an ozone generator or any other electical appliance that could be creating ozone in there?
That stress appears to be a form of heat stress possibly related to undertranspiration which I'm guessing is either to do with gas exchange or the fact that you have a sealed room that cannot evacuate enough heat. And/or possibly not enough oxygen during lights-out.
My bet is something to do with your CO2 management and lack of air exchange. When you turn up the lights, you are not only turning up light intensity – you are creating more heat. That heat has to go somewhere, otherwise leaf temps build up.
What is the difference in temperature when you have the lights dimmed to when you turn them up. Ie; what was the difference in temperature between those two days before and after turning up the lights?
Prawn Connery
Well-Known Member
That's becasue UVB thickens the plant epidermis which "hardens" them off after exposure. There are other photomorphogenic responses to UVB that defend the plant against radiated DNA damage. All forms of light are radiation.
Starseed.extracts
Member
It sounds like you are in the right department of solving this!
My topsoil looks muddy because I use nectar 4 the gods nutrients, and compost teas, in promix hp.
I used to use Mills and the soil never looked like that but I switched to nectar and teas and now it does.
My ppm right now when lights are on is 1500. When the lights go out I have an exhaust fan that kicks on if the humidity or temperature spike. So that brings down the co2 at night quite a bit im sure. So it's a sealed room other than the exhaust that kicks on at nighttime, but only if humidity spikes above 70 or heat spike above 78°F.
No I don't use an ozone generator and never have.
My temperature between the days where the plants looked fine and the leaves burned up did not change much because I turned up my mini split to keep my temps in check. The whole time temps were around 77°F . I am thinking the air exchange thing might be the key here. Cause I use a tank to keep CO2 levels high, but there's never any fresh air exchange. Idk I am stumped but it sounds like your on the trick track here. Appreciate it. This issue is driving me bonkers, as I said I have successful harvests with the same lights in isolated 4x4 tents for over two years. Only putting them in this room in an array is when I started having this leaf burn issue
DoubleAtotheRON
Well-Known Member
I run HLG 550 V2's and have not really had a problem with light burn. Im sealed up tight, and running a propane CO2 genny, and and AirROS ozone genny. No air exchange ever. I run the lights at full power and at 24 inches from the canopy. 83-86 degrees, and 63-67% RH in week 5 of flower. Only prob I've had was my fault, and that was N toxicity, blocking my K uptake, and did a slight burn in the tops... backed the N down, and it stopped the narcotic instantly. So... from what the OP says about PAR and distance, I'd say there's a toxicity, or something antagonistic nutrient wise going on.
Prawn Connery
Well-Known Member
So your CO2 system does not automatically exchange air when CO2 levels are high at night, when you plants actually need oxygen and not elevated levels of CO2 (which are detrimental)?
I've seen this before with CO2 growers who forget their plants breathe oxygen at night and continue to give them too much CO2 when the lights go out.
A proper CO2 system should reduce CO2 to below 800ppm during lights-off.
I've seen this before with CO2 growers who forget their plants breathe oxygen at night and continue to give them too much CO2 when the lights go out.
A proper CO2 system should reduce CO2 to below 800ppm during lights-off.
DoubleAtotheRON
Well-Known Member
You talking to me or the OP?
Starseed.extracts
Member
I have the autopilot system for my CO2 regulation. It does turn off at night, and my exhaust pushes out hot and humid air, along with CO2, so I'm sure it goes down to somewhere around 400 at night time, but I will check . I have never heard of any growers running an oxygen tank at night but is this what your suggesting? I couldn't pull in air straight from outside it's coooold here rn in Michigan
Starseed.extracts
Member
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Starseed.extracts
Member
Here are my temp and humidity swings over the past like 4 -5 days
DoubleAtotheRON
Well-Known Member
Looks good to me other than you're pretty cool at lights out. Try to keep the swing within 8-10 degrees.... but I don't think that would cause what you got going on.
Prawn Connery
Well-Known Member
OP, sorry.
What I'm trying to figure out is the correlation between the light being turned up and the leaf burn. If it's not light, then it's heat in the room. And if it's heat then I'm wondering if the aircon constantly being on is producing too much ozone? Im not entirely convinced that's the issue as it would affect the overal plant, but it could be a contributing factor. The ozone generator you have, I believe, does not produces large amounts of O3 (30ppb), but relies on trioxidane to purify.
Nutrient issues can obviously be caused by excessive heat because evaporation in the root zone increases nutrient concentration and increased transpiration can rob the plant of moisture whilst drawing up excess nutrient. But CO2 slows transpiration as the stomata do not open as wide (they don't have to because of the higher concentration of CO2 which requires less gas exchange). This, coupled with the fact more photons are photosynthesied instead of being converted to heat that builds up in the leaf, is why you can have higher temperatures when running CO2.
However, if CO2 levels are higher at night, then the reverse happens: stomata need to open more to exchange oxygen as there is less of it in the air. This can lead to too much transpiration. Reverse photosynthesis (which happens when the lights are off) produces CO2 and H2O, so more water is lost, possibly causing the leaves to dry out – which can burn them.
As I'm not there, it's hard for me to pin-point. But one thing I do know is the problem is not light stress.
DoubleAtotheRON
Well-Known Member
Agree.. and yes, my unit is an H203 generator (Trioxidane at 30PPB)... I suppose it would be helpful to know the transpiration rate. Are they needing feed after 36 hours? or 6 days? Good info man.
Prawn Connery
Well-Known Member
You can see where the aircon is really having to work over those first two days.
Prawn Connery
Well-Known Member
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?
DoubleAtotheRON
Well-Known Member
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.
Prawn Connery
Well-Known Member
No, in a sealed environment the plant produces enough oxygen when it photosynthesises during lights-on. The problem is when the CO2 is left on during lights-out.
DoubleAtotheRON
Well-Known Member
I believe he said he was venting at lights out?, and had a photocell that shuts down the co2?