1st time seeing this...help please. Have pics

Ok so I'm vegging some Pure Power, Pure Gold. These are clones of an earlier batch so it's the same strain and plant. I'm using Fox Farms soil with Fox Farms nutes. I always wait at least 3 weeks to start using nutes with the fresh Ocean Forest potting soil because it has it's own nutes. So I noticed some of the plants leaves are turning light green to yellow to brown and crispy. This started before I started using the nutes (ie, Fox Farms Big Bloom, Big Grow). I keep my temps at 84 degrees and supplement with CO2 at 1200ppm. Any ideas? Low nitrogen? Low Iron?

The first pic shows the progression

how often do you water and feed your plants?
it could be nute burn or ph.

Looks like a P deficiency to me

I was thinking it's nitrogen but the growth is not stunted. That's why I'm thinking it's Iron, with the way the leaves are turning yellow but the veins are still green.

Anyone?.......Bueller........Bueller...........Bueller.....

looks like your low on all nutes ... that or your locked up. But it's gotta be the nutes if you haven't been feeding

there def getting burnt flush them with purified waterph 5.5 asap for a couple of feeds