Discolored and twisted leaves

The small leaves around the bud sites on all of my plants have started to turn dark and become twisted. The large leaves are not at all affected. I'm using the Lucas Formula, so this *shouldn't* be a nute use (but I'm not rulling that out). I just discovered this morning that the res temps are too high, so maybe that's the issue.

Grow Details -
DWC Drip Feed Hydro system
Lucas Formula - GH based nutes - flowering profile - 920ppm
pH - 5.6 and stable
6 - 42w "soft-white" CFL's over each plant; 2 - 26w "soft-white" CFL's in front
Room Temp - 84 average; 88 high; 79 low
Res Temps - 82 :wtf:

Any thoughts or suggestions would be appreciated.

yes i agree high temps , i had a very simmilar outcome white some widow when my temps were raised to the near 90's.

I believe your on the very edge of nitrogen toxicity

heat :smokin:

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Originally Posted by Ganja Guerrilla

I believe your on the very edge of nitrogen toxicity

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Yeah, I wondered about this last night, actually. In *theory* this shouldn't be possible using the Lucas Formula, but.......

I know that having reservoir temps too high will lock out nutrient absorption. Assuming that P and K have maybe been locked out, could that account for the nitrogen toxicity?

heat doesnt make new growth overly dark green, but nitrogen does


lots of photo examples at my site ....look in fert burn sections & Miracle Grow sections
Web Gallery Wizard™

the dark green could have been there before the leaves started curling, and since he's in flowering cycle, unlikely he is adding nitrogen, that being my reasoning, as well ... :smokin:

I vote for N tox as well.
However I also see single bladed leaves that don't look like 'sugar leaves'- are you certain you do not have any light leaks?

additionally if it were heat, the leaf margins would curl Upwards to conserve transpiration

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Originally Posted by the image reaper

and since he's in flowering cycle, unlikely he is adding nitrogen, that being my reasoning, as well ... :smokin:

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This is not a correct assumption. As I said, I'm using the Lucas Formula for my nutes.

During flowering it calls for a 0-8-16 ratio (in ml per gallon) of GH FloraGrow, FloraMicro, and FloraBloom. The FloraMicro's NPK numbers are 5-0-1 (along with a bunch of micro nutrients), which means every time I top off my reservoir I'm adding some nitrogen to the system. Not much, but some.

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Originally Posted by stinkyattic

I vote for N tox as well.
However I also see single bladed leaves that don't look like 'sugar leaves'- are you certain you do not have any light leaks?

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Although I am not 100% certain I think that's a small fan leaf that's growing an inch or so beneath the budsite and the angle of the camera makes it look like it's something else. I did notice that a couple of the fan leaves around the budsite I took the picture of were starting to darken a little, as well.

However, it's also possible I might have a light leak. I'll have to double check that tonight.

Back to my second question....Can the N tox be caused by having res temps out of wack? Or am I looking at something drastic like needing to drain and refill the reservoir?

Draining and refilling the res isn't necessairly a 'drastic' move- how often do you switch out your res anyway?

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Originally Posted by stinkyattic

Draining and refilling the res isn't necessairly a 'drastic' move- how often do you switch out your res anyway?

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I don't. With the Lucas Formula you're not supposed to, actually. Lucas originally recommended switching out the res when you started flowering, but he has since changed that recommendation and now suggests switching out the solution only if something goes drastically wrong with pH or the ppm's get severely out of wack.

Also, since refilling the reservoir involves bringing home several gallons of distilled water (tap water at my place sucks), I consider that "drastic", or at least a serious pain in the ass lol.

EDIT to add: Also, part of my concern is to identify the underlying cause of the N toxicity. If it's a problem with the res temps, then I know what the fix is. If it's the nute solution, then I need to research more to know what's wrong. Although, I'd be somewhat surprised since there are a LARGE number of growers who just rave about the Lucas Formula. Of course, it's also possible that I'm a complete noob and I've managed to bungle the Formula lol.

Start with your temps.....

The N toxicity has occurred in the last 24 hours and I have been using the same nute profile for 3 1/2 weeks now. So, I have to ask myself what has changed in the last day or two?

Answer: I added an airstone to the bottom of the res.

Now, I've been using a small garden pump to "circulate" water through the reservoir. But in thinking about it, the pump sits on the bottom of the res, and the water re-enters the res via the drain - also on the bottom of the res. I don't think I'm actually getting as much circulation as I thought.

When I add nutes, those are poured into the top of the reservoir. Since the solution isn't circulating as much as it could, it's possible that the solution is more concentrated at the top than at the bottom of the res. Normally simple diffusion would solve this, but as the plants have gotten bigger their roots are taking up a lot of space in the top of the res. Circulation is reduced even more, and diffusion is occurring at an even slower pace. Since the roots are pretty long they were getting a mix of strong and weak nute solution and weren't having problems until I added the airstone.

Also, when I test the pH and ppm, I do so by taking a sample from the drain - the bottom of the res. So I'm guessing my samples aren't accurate.

I'm guessing the airstone is mixing up everything at a faster rate. The over-concentrated nute solution is suddenly spreading through the whole res and the plants are getting sick. Any bets that if I take a sample from the top my pH and ppm are going to be off? :wtf:

yes an air stone definetly can change the ph ....especially if the intake was around an acidic condition

hope all goes well help_needed.

as tactful as i can, is it your intention, hn, to be ganjaguerillas fluffer?

I mean, you two already know each other and didn't you tell me gg was the man?

I just wanted you to know how it looks to me. I know ricslat is gg's girl and defender, but after our last convo i didn't and don't think that of you.

Cannabis.com folks. i know you're going who cares or wtf. well it's nice to know when ppl are trying to play ya. you want proof go to grasscity. i will neva go back

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Originally Posted by 420freedme

as tactful as i can, is it your intention, hn, to be ganjaguerillas fluffer?

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The fact that you prefaced this statement, 'as tactful as I can', shows that you already know that you're being less than polite here- Please check your profile messages.

If you have issues at another forum, please leave them at the door.

Thank you.

Hey everyone,

Thanks so much for all your help and input. Based on the suggestion of a grower on another forum I located a forum where Lucas posts and answers question regarding his formula. It was his opinion that the Formula was too low in Nitrogen to cause true toxicity and that my reservoir temps were negatively impacting my grow. He also added that he's experienced the same problem when his temps got out of wack.

Based on that I took some corrective action and brought both the ambient temperature and the reservoir temperature down to acceptable levels. Closet temps are now running between 76-82 and the reservoir temp is 75. I should also add that my initial reservoir temp was just a rough guess, based on how warm the water felt to me. I think my guess was actually way off, and the temps were probably significantly higher than 82 :(. And I've learned my lesson - no more guessing lol.

There a little bit of new growth that's come in over the last couple of days and it looks normal, so hopefully I've got things under control. On the other hand, I just discovered a large number of leaves along the back of the grow (where there's less air circulation) are showing some pretty massive pH spotting an damage. Hopefully that's also heat related, but I'll be watching it closely. If the damage continues to spread, you all will be hearing from me again.

Thanks again for all the help and support.

heat is a deceptive bitch. I just had to replace a 6000btu w/a 15000btu and it's fall. i added 1k to the room and the temp went up 8-10 degrees. i thought the 6k could do it, but i was wrong. my 4way hybreds are picky, picky, and started yellowing in 2 cycles of light. yep that fast. no central ac is making this fun and challenging, but hey, what else would i be doing? 9to5...lol

gl hn and heat will cause those spots too. heat + not much air movment?

I would wonder about the solubility of atmospheric N at different temps- our atmosphere contains LOTS of N2- I don't know off hand how it could become available in your res, but Delta9Haze might be around somewhere... ? :D

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Originally Posted by 420freedme

gl hn and heat will cause those spots too. heat + not much air movment?

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Interesting observation. Earlier in the summer I got the bright idea of buying a portable evaporative cooler to use to try to keep the temps in the closet down. It worked great for a couple of hours until the RH in the closet got high enough to stop the evaporation from happening, then it just became a fan - an expensive fan, I might add lol.

Because of it's size, it has to sit on the floor. And because there's still water in it, I couldn't angle it upwards. It didn't matter at first, but after I added in some mylar to help with lighting, I think that the airflow to the top and back of the grow was restricted. And guess where all the spotting is :rolleyes:

Oh...and turning the fan off completely dropped my closet temps about 8 degrees. Guess that fan motor puts of a lot of heat on its own.

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Originally Posted by stinkyattic

I would wonder about the solubility of atmospheric N at different temps- our atmosphere contains LOTS of N2- I don't know off hand how it could become available in your res

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Um...well...I *did* add an airstone to the reservoir a few days ago........:D

check this out hn. i use the ac as a dehumidifier (i live in humid hell and underground). w/6OOO btu staying on all the time kept rh at 4O-5O%. this 15OOO has me watching rh rise. guess why.

the ac keeps the room at 75 lights on 6O off. problem is the ac is too big to pull out the humidity. reason: it doesn't stay on enough. it works in short burst, so guess what is on tap for today? yep, work a dehumidifier into the room. 3OO sq ft w/2k hps. 1 of 4:)