Problem caught early, unsure what it is! - Pictures + Stats

I posted this in the sticky as well, but seeing that no one reads it... I'll be safe and post here too.

1) PICTURE OF PLANT *** VERY IMPORTANT ***

View attachment 1854049View attachment 1854060

2) Growing indoor or outdoors
Indoor

3) Watering schedule
1 min on, 5 min off low pressure aero

4) Growing Medium
2 inch rockwool cubes

5) What stage of growth
Day 19 Flower

Aditional information:
Temps 67-80(lately never higher than 80)
PPM: 380 or so
Ph: 5.8
Humidity: Unknown(could be on the high side)

So yesterday this started to form... Now the plant is getting closer to the light, and that leaf is dead smack in the center of the lights area of cover. The side pointys on the leaf are curling up a bit which suggests that it's hot, but I've seen this plant when it gets to hot and it just curls the F up. Like Claws. Now this is on the top portion of the plant, and I haven't seen anything else like this on any of the others...(5 others that are on the same day, same strait, same conditions as this).

Here's my question, what is it? Is it mold? or is it just nute burn? Any input appreciated. Thanks in advanced.

Im a soil guy, but as far into flower as you are, seems like your ppm's are quite low. Thats just a thought. Good luck and good growing

gotigers0420 said:

Im a soil guy, but as far into flower as you are, seems like your ppm's are quite low. Thats just a thought. Good luck and good growing

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You're right, ppms are really low. I got some smaller plants that are 2 weeks behind the others living off the same res as the larger ones. The ppms are a little low, I could most likely raise them, but the real question is: Is that my problem? or am I facing something worse?

Slivers said:

You're right, ppms are really low. I got some smaller plants that are 2 weeks behind the others living off the same res as the larger ones. The ppms are a little low, I could most likely raise them, but the real question is: Is that my problem? or am I facing something worse?

Click to expand...

I have to think thats part of the problem.

leaves nice and dark and healthy looks like the start of oxygen starvation at the root base somewhere, if you are using ph 5.8 that is correct, and your ec (ppm) is correct your temps are correct, have you tried liquid oxygen, funny it has just started, could be the mass size of the plant vs the mass size of the root base vs water vs oxygen starvation, how many leaves and what height on the plant is that leaf damage.

if it is one leaf dont worry until it happens elsewhere, if it does not then it has been possible light burned.
if it happens only in the same area then it is light burn simple as that.
always worry about the new growth coming in not the old growth, the new growth shows the true health of your plant.