Over fertilization. Give the plants a good flush, and a fresh batch of ph’d nutrients on the back end
Looks like over watering,not a expert but in my experience a little less goes along way,otherwise they look awsome an as big as they are ypu obviously know what your doing.your gut feeling is going to tell you what’s wrong.9 chances out of 10 is usually is what you had originally thought.Happy growing
I agree, it looks like nute burn. It could be from accumulation of too many nutrient salts in the soil or growing media. A EC/PPM of the soil, media or reservoir would confirm or rule this out. It might be a nutrient toxicity from a pH imbalance, certain pH can make some nutrients overly available and result in nute burn like symptoms. The pH or your root zone would confirm or rule that out. I would expect normally different “burnt” marks or splotches if it was a deficiency due to pH, but you never know and knowing the pH would certainly help.
The big fan leaf in the middle of the picture does almost look like “over watering bloat and drooping”, but when looking at the upper leaves, you see upward curling and yellowing and “burning”/browning at the leaf’s edges, this does not happen with over-watering usually. However over watering can cause pH imbalances and other sometimes strange occurrences such as pythium and fusarium that can sometimes lead to ugly burnt looking leaves, but again, I don’t think this is what this looks like.
Not sure if I have same problem only using distilled water and rain water ph 6.5 6.8 just started using nutes @ 50% strength plants in 5 gallon buckets use 1 gallon water per plant runoff ph 6.8 and soil
They look awful dark, but the piks are dark also.
You cannot over fertilize using 1/2 strength; IN fact, that may be your problem. Looks pretty big for 1/2 strength nutes. ???