I sometimes get a few leaves that look like your week 3 pictures after I move a young plant into the flower room. I chalk it up to either light intensity change (from 400w to 1000w), humidity change (~50% to 40%), or a sudden increase in nutrients flowing through the plant as it begins to transpire more water through its leaves (nute burn). Hard to say, really, but usually when a leaf is burnt from the tips like yours, it's nutrient overabundance.
Plant "stress" is a generic term for any number of conditions, nute burn being one of them. So when you say that your plant was stressed and not nute burned, it doesn't really serve to explain what has occurred.
I see that this isn't the first time this has been suggested, but you might consider being a little more cordial to your fellow LEDers. After all, we're using our own time to encourage and help you.
The "burn" was the result of a unplanned shutdown that allowed the soup to heat up and no circulation (BLAH!).
I FUCKED UP and didn't fuse something (since corrected).
This grow was taken from the cloner straight to bloom phase (as an experiment), so I expected a reaction, even though I kept the PPM's at around 1000 in the beginning.
It was a 50/50 mix of veg and bloom nutes for about a week.
Also, the clones were 10 weeks old.
Nothing has resulted in the leaf burn like I show before and I have been growing this WW strain for four years.
FYI the cloner runs @ PPM 125, R/O 65deg F.
I get a few leaves that show nute burn almost every time I do a crop, and that may be the light change or soup concentration or just funky leaves.
I really try to be "cordial" and appreciate any input, however, the leaf damage was not caused by over fertilization IMO.
I have very good notes and pictures on previous grows (20+) of this strain.
As long as I keep the PPM's under 1850 there doesn't seem to be any problems.
Sorry, but leaf burn like that doesn't come from temporarily high nutrient temps either. Like I've said, *I* can only go by the pictures but it certainly "looks like" nute burn to me.
If the 1500 ppm makes things worse, we'll see. What kind of nutrients did you say that you run again?
Disclaimer: I still use HID and I'm NOT an LED expert. All of my LED knowledge is from other parties or research so I can't say from first hand experience one way or another. I also run a medical grow consulting business in SoCal.
Floricious Plus, Blend (tea) Kool Bloom (liquid and dry).
Like I said (but I guess it doesn't matter) I have experienced "problems" (nute burn) when I ran above 1850 PPMs, but as long as it is below 1600, no problems.
The fogger is used to fill the space between the net pot and the top of the soup level (about 3-4 inches) with "fog".
So much better then drip lines (clog city), but there are caveats to using them.
Right now I am looking at epoxy coatings(for the foggers) as they (foggers) are not available in stainless (single unit) and there is a reaction between the metal(s) plating and the soup because of the caustic nature of the soup.
I have killed crops because of metal leaching and it was a bitch to find.
Advice: NEVER USE COPPER ANYWHERE that is gonna contact the soup.
I love GH nutrients, I recently switched to the nova series.
Somebody here (prehaps more than 1 somebody) claimed that LED grows require a weaker mix than HID grows. I, obviously, woudn't know since I don't use LED but *if* that's true, perhaps that's where the confusion is coming from.
Yes, copper and salts = bad. Titanium works in saline conditions but I doubt you'll find a titanium fogger either so your epoxy idea might be the ticket as long as the epoxy isn't reactive either. I'm sure you'll figure something out...
Disclaimer: I still use HID and I'm NOT an LED expert. All of my LED knowledge is from other parties or research so I can't say from first hand experience one way or another. I also run a medical grow consulting business in SoCal.