Crazy issue I don't have an answer to

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Geezus I see this same problem everywhere. There is no escaping it, we are all doomed. 8 grows always the same issue. I've never had a perfect grow I've changed everything and always day 25-45 I get the same problem. This grow I think I have fixed it. I changed two things. One I changed ferts and two I have stopped pH'ing my water. I am in promix also and what I believe you are seeing is an imbalance in your promix because your are pH'ing your water. Promix is peet and lime it is setup to give you a 6.0-6.5 pH in the soil. When you add pH adjusters to the water your creating an imbalance in you media. Get a soil pH tester test pH of the media. I will bet your pH of the soil is 6.9-7.2. this is too high. Start feeding without pH'ing the water and after 3-4 waterings this will start to stabilize and the media pH will start to go down. It's either that or the nutes I was using were just crap. Anyways your setup is much more elaborate then mine so you probably have more experiences then me, but figured I would chime in and say my two cents.


interesting and informative... you've given me some things to ponder. Thank you Oterplord for sharing your insights. much appreciated 👍


dont disregard the importance of checking for the virus though. what you describe is how that virus effects the plants. im not trying to be right, just sharing my experience. what i can tell you is that once i started new, and i mean like, sanitized replace all kinds of gear, everything changed back to "normal" and i never looked back. What Oklahomaterplord has recommended would be a much easier place to start and you could implement that right away. give it a go while you've got a cut out for lab analysis.

also, running the promix and and cutting it slightly with perlite dont mean much. Thats an old style of gettin with it. I think thats what GNick was trying to hit home. That medium holds a lot of moisture and if your giving it a lot of inputs daily it aint going to work. you would prolly need 50% perlite or more. Just rock the coco or rockwool already. Make it easy.

dont think about watering with nutrients as "feeding". the feeding is in the solution. i think of the "inpurts" as oxygenating the root system. i go lower ppm's but frequent inputs. the ppm's come up with phase or growth/maturity...whatever you want to call it. we all got our methods, lol


Can you out GRAV The Gravmaster???
Just a thought... do you purge and clean your feeding system... just like at a bar... the cleaners purging the system left some chemicals in the system and bar tender ended up serving said chemicals in beer burning esphogus... just made me think if system has been purged or cleaned... again not using same crap to clean beer lines... but just an idea that came to mind...


I've seen this same look on some of my plants but haven't solved it. I don't think it's light burn, even if it does look like a burn. I have wondered if it might involve ventilation. My guess is that something about air flow might dry or damage the tips of the leaflets. The necrosis is as if they were way past senescence.


Thank you for the questions. Nice to see someone that doesnt feel the need to flex on a complete stranger on an anonymous forum. I kind of figured I would get a couple haters but thought that those people had largely grown up. Apparently not.

In any case to your question. Yes, we have done a tap water analysis. There were certainly things that were surprising like chloroform and lead but honestly nothing out of the ordinary compared to other grows we have in the same area. Initially the water was one of the first things we thought of because the water was coming out super high in dissolved solids… like 320ppm high. So we installed a very large RO system.. that of course cane with its own issues because once you remove all the calcium it makes it hard to PH balance and eats all the minerals out of your probes so they dont last very long. Long story short the tap water ended up coming back down to about 90ppm after 60 days or so but we kept using the RO since we had already spent a bunch of time and money putting it in. This last month we ran one room with one side on tap water and the other on RO water, the results were the same.

Honestly Im fairly confident we are experiencing light burn but I dont know how that could be possible given that there is very low light in the rooms. Typically we will run bloom rooms around 1000-1500 PAR but these rooms will get what looks like light burn at a meager 400 par… which is less than they were even vegging under.. but we have zero problems in veg. Its almost like something is opening up the stomata to accept more light than it should or something. Its just all around confusing. To make matters more confusing we have 8 rooms side by side by side. The last room in the row will flower plants just fine these last two rounds.. all the way through completion, no issues, lights at 100%. This last time room 1 was successfull too but did see a little bit of burn. But ALL the other rooms in the middle just cook. All have the same lights, water, nutes, temp, humidity etc.

One difference between this facility and our other ones is these rooms we had built with trench drains. Supposedly the plumber put in pea traps though so no gas should be able to come up through them but that was one thing I was concidering… methane poisoning, particularly because room 8 is the furthest from the main sewer line.. but then room one, the closest succeeded. And there is also no smell emanating from the drains and in the past when I have had pea traps dry up and let gas in you can smell it.. no smell here.

Where does your waste from RO
system dump? Is it before or after the p trap. The concentrated chlorine will sometimes offgas and can build up in a sealed environment. And did you test water for fusarium


Come on guys . The bottom of the plant is clean no issues . The tops is crisp burnt . Light is closer to the top not bottom.
He is not checking his par lumens . This website will help .


What state are you in?

I'll tell you the fix. Monsanto has infiltrated your crop with engineered nanobots set on boof mode, and have the antidote price set at 1 million! Just kidding we don't need to worry about that until federal legalization.

Your issue is P bound in the promix. Could confirm with tissue analysis, medium analysis (M3 type compared to saturated paste). I can tell you effectively have less than 5ppm P available in solution.

How are you phing. Never grown with bottles but Gh pH is phosphoric, which is binding to excess Ca and waiting for microbes or exudates to release. Today's plants were not bred for slow P uptake. And the all-in-one Leds don't signal P uptake if it's missing the right spectrum of red. You're in a peat medium but not paying attention to phosphorus solublizers. Citric acid is the fix. Unless it drops pH too low. The fertilizer game is constantly changing shape. "Low P" is being pushed by companies contracted with foreign P mines who can't get good rates anymore. Responsible companies have bought up all the waste water contracts for P recovery. Struvite will be a common P input moving forward in Cannabis as it is easily released by organic acids and the ammonia offsets that acidity.

If you put a bunch of acids in your soil beforehand and buffer to that, the plant will fill with citrate, etc. I put every acid known to man in my soil before adding silicates/carbonates. That's why the hippies are so jazzed with microbes and ferments and cooking soils for months. It's all about the P cycle and having excess carboxylic acids so the plant doesn't dump all its resources into exudates (which it won't even do without proper light spectrum) . You see this exact problem all over the web always early bloom under Pimple stripe (what we call white led with red specs here and there) with P demand rising.

I asked what state you were in because there is no logic why things get out of whack other than microbial demographics. I used to grow mushrooms. Standard practice was to use isopropyl. Long story short anyone using isopropyl is working against themselves as the first microbes to return and flourish are the nastiest most hell bent desperate motherfuckers that don't play along with anything else. Same type of rules apply in soil. Pro mix is like an open petri dish. Some brands of nutes will make your soil smell like shit and what do you know, issues in those rooms.

Sorry to say you will never catch up to a -P issue in Cannabis. Top Cannabis growers use ungodly amounts of P in veg and foliar zinc boron magnesium (that's the only negative to high P in medium). Lots of people will tell you that Cannabis needs low P, but those people got red noses. I literally here the gurus talk about "luxury P" like it's a bad thing. Cannabis literally needs to load its leaves with P or you'll end up with a horrible product feeding enough soluble P throughout bloom. #1reason people say organic is better. The leaves have enough P in the right forms when things are working smoothly and it pulls all the sugars out of the leaves and into the buds. All the organic hippy bud that sucks, sucks because of -P and there's alot more of it than the organic community will admit. Because they don't know shit about nutes and Negatively influence the community with their vain hippy prayers and empty meditative ways.
your like a toxic twat.
not all organic growers are hippys.
I am definitely no friggin hippy dude and I use slow release ferts … funny how some know a little and then think there a grow god


looks like potassium problem

I was having an issue with promix, where it was dropping my RO down to 5.3 maybe you should check the run off see what its reading or even a direct soil ph test


OK, so here it goes. I am a long time commercial grower for over 20 years. Ive been growing for over 25 years though... first couple weren't terribly successful. I havent been on a forum for probably 15 years.. been too busy and had kids and life happened etc. As much as it pains me to be on here I have an issue I cant seem to solve and generally speaking I dont know anyone who knows more than myself and the other proffessional growers around me... with that being said noone seems to be able to figure out my current problem and we have over 100 years of indoor marijuana growing under our belts combined. I can honestly say I never in a million years would have thought I would be reaching out to strangers to help but if there is one thing I have learned over the years is pride and arrogance have no place in the growroom, so here I am.

Long story short we have a new facility that just came online with a couple hundred bloom lights in it... this is probably my 20th such grow Ive managed and I have never had an issue I didnt have the answer to. I can humbly say I have no answer for this current problem.. Ive tried everything I can think of and hence Im here hoping someone with a different perspective might have an idea I havent thought of.

Essentially the issue is the plants will veg just fine but once they go into flower they will burn up in 1-3 weeks from what looks like light burn but I dont see how thats possible as the par is well below average... even with the Gavita LED 730E turned all the way down they will eventually all burn up. Here are the basic facts

Strains: lots of them, from Cake to Silver Haze to Lemon OG and everything in between
Substrate: HP Mix #4 mixed with Perlite. Roughly 30% pure perlite mixed with 70% HP Promix #4 (Ive successfully run this mix in commercial grows for over a decade)
Nutes: GH 3 part (yes I know, please spare me the lectures... again, been using it for over 15 years and currently use at other facilities with no issues other than its GH and generally sucks.. this choice isnt mine) Cal Mag once a week (although we have tried with every watering, and not using it all... all ended with the same reult
PH: adjusted to 6.. have tried RO water and tap water.. same results (buffering RO is a pain though as many know already)
Lights: Gavita 1700E LEDs. This is newer for me but again we are using them at other grows with no issues other than having to run the rooms a bit warmer to keep the VPD and leaf temp up.
Full enviro control: 10 tons of AC per 20 lights, Quest Dehuies AND humidifiers in every room to keep the VPD perfect, CO2 injection via a central Cryo tank.
Enviro specs: will fluctuate a bit but generally speaking were running 80degrees, 65% humidity, 1200ppm CO2.
Pests: Nothing other than the occasional Thrip here and there but they are controlled pretty well with Neem and pyrithrin bombs.. I should have them eradicated in another couple weeks until they crawl out of a new bag of Promix then I will eradicate them again if the preventative spraying lets any slip through. Of course I spray with lights off and wont turn them back on until the next day.
Nutes: running half strength currently to postpone the burn .. watering with about 800ppm.. runoff is generally good at first (under 1500 and PH6) and then as time goes by it will rise because the plants arent uptaking anything.

Please see the pictures. Some strains will burn up faster than others but eventually, they will all cook. 1 out of 10 rooms will make it.. most dont.. there is no difference I can tell from one room to the others. We are using this exact setup at other large commercial grows with zero issues.

Any ideas would be greatly appreciated.. you can generally assume anything basic I have probably already tried but hell, Ive even tried very expensive complicated things to fix this to no avail. It does not seem like a viroid or fungal infection.. Ive dealt with both many times over the years... but maybe this is a new one noone has ever seen? who knows

PS: I know the lights in the pics are Hortilux lights.. just a couple rooms are running those.. the rest are gavitas.. specs are essentially the same and the rooms do the same thing regardless of the lights it would seem.. Ive also tried Gavita 1000w DE's and the exact same thing happened. Its a real mystery. They just seem to essentially stop growing and burn like this once they get into flower... I cant make any sense of it. Everything from substrate to nutes to lights we have used successfully and still do at other grows.. like literally the same pallets of substrates and nutes etc.

One small caveat ... Initially in this building we bought some equipment from another grower.. it took us about 4 months to realize the hoses were leaching Bifethrin and Thiabendizole into the plants... but at very small quantities.. like 50 ppb (not ppm) when the soil was tested. We have since replaced all the hoses and pumps and reservoirs and this hasnt seem to fix anything... although there is a chance they may have seen small amounts of it when they were in dixie cups but again they all veg just fine.. this only happens 1-3 weeks into flower and it should be way way way diluted by then.. additionally the previous grower has said he didnt have any issues ... noone seems to really know where the thiabendazole came from though.. Im guessing it was in some kind of multifaceted fungicide the last grower was using to conteract bud rot or PM... we dont have either.

Any wild ideas or even basic ideas are welcome. We are really starting to feel like were in the twilight zone or something... maybe this building was put on an indian burial ground.. who knows. Ive also checked cameras to see if maybe a digruntled employee is sabotoging things and havent seen anything suspicious plus, we are all happy so that really wouldnt make sense although I suppose it isnt impossible. But even if that was happening what would cause light burn at like 425 PAR at the canopy top? We are way under the amount of light and nute strength we would typically run at but all that does is postpone the inevitable it seems.

In these pictures you will see the necrosis on the leaves.. unlike with nute burn the dead sides dont go from green to crispy.. they are almost soft when they first die.. even velvety.. and then after a day or two will turn crunchy. So So weird.

Thank you to all who read this, Noob to expert. This is completely unlike anything I have ever experienced before.
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i've read only the original post, end of year crazyness here,
80F Air temp is a bit lower than optimum for co2, you want 83-85f running co2
leaf temps at around 80f with co2 would be close to optimum.

With leds its better to have them a bit closer dimmed down than far away full blast, you will raise LST easier this way.

At night vent out to clear Co2 and bring co2 to atmospheric level for the whole night also to vent out any toxic gas that could be building up in your growroom, you could be having toxic gases build up at night like formaldehyde or other toxic gases giving you your phantom deficiencies/problems,. i've seen it some times over the years and the symptoms are pretty close to what you have here.

anyway that would be my line of approach to this, i wish you the best of luck, and get back here with any news.
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Really does not matter . This commercial grower will have bugs soon. He is wearing outside clothing into his grow faciality .
From what i see the place is filthy . That is rule for commercial growers . The entire warehouse should be cleaned daily.
I see water on the floor spilled next to the barrows . Filthy
Real commercial growers shower change into coveralls hair nets before entering the grow . Not some guy in jeans . it will for sure fail as soon at the weather warms up outside the indoor crop will be doomed .
Sorry to say all this but if you want to run a commercial grow . No half ass steps .

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