help identifying leaf issues

Recently i've noticed a few scattered leaves displaying signs of deficiencies/over-nutrients. This is my first grow, and although ive looked online i cant pinpoint it to one problem. Can anyone tell me whats wrong from the photos, and what i need to change to fix it.

The two plants have just been put on 12/12. They get nutrients with NPK 18-9-26 diluted 1g/l 1-2 times a month. They're watered with tap water ph'd to 6.3 whenever the first 1-2 inches of soil feel dry, leaving 20% runoff. Roots are healthy and white. They're under a 600W HPS with temps at around 30C during light period, dropping to 23C when lights are off. Humidity is around 30-40%.

What kind of soil is it? if it's PH amended soil like fox farms, I would bring your PH up a little higher. I usually go with 6.6-7.0 Also get some more air flow if you don't already. I'm no expert but that would be the first thing i do. When in doubt- Process of elimination

This is my soil mix:



my airflow should be pretty decent with 3 pc style intake fans behind the plants, 2 pc fans for circulation and a in-line outtake fan.

over watering...raise your humidity a bit and those tips will straighten out

humidity for the tips, ill try raising it, thanks - what about the discoloured leaves?

over watering causes the roots to drown and not uptake nutrients. Overwatering can also show damage for upto weeks after. you will most likely loose those leaves. To get her back on track again give a small dose of N ,cal,mag on the next watering, plain water after that then cal, mag dose next.

ill try that out and post back if the problem persists. In the mean time if anyone else has suggestions/ideas lemme know

I don't see cal listed on bag.maybe nutes u use has it?very inportant

yup, add cal/mag

That plant is very, very, dark green. Thats usually a sign that you are definitely feeding enough