Upper leaves clawing under and lower leaves dying

Hello again community!
I have a young lady with a ton of issues I hope I can resolve without stressing her too much! The top leaves are clawing or curling at the tips, under themselves. Along with that the lower leaves are looking magnesium deficient: crispy with yellow and brown inter venial chlorosis/necrosis. Also showing dark red/purple petioles/leaf stems! WTF! I'm thinking Ca, Mg, P, N, or possibly (but doubtfully) overwatering.

Medium: FFOF, 1.5 gal pots
Light: 1000w HPS, 18/6, 23" from lamp,
Temps/Humidity: 76'F day / 69' night, 40%RH
Strain: Unknown bag seed
1/26- Seedling strength FF Grow Big 6-4-4
Gave her a seedling strength dose of Cal-Mag+ on 1/30
Otherwise water @ 6.5pH about every 4-6 days, soil gets dry.


The last pic is of a different plant showing similar issues...

Not such a mystery. Veg food too high in P. They look plenty green other than the burn. Why feed something that hasn't even put a dent in the original nutes in the soil? Putting more nutes into the soil than what 20 plants that size can use isn't ever going to make a plant grow faster, bigger, or more potent. Don't let anybody talk you into flushes or replanting or all the other jive. If those are the planters you are going to finish in just start watering them when they get dry. don't add anything just water. you won't need to change that process untill you start to bloom. them your typ of nutes will change and you can feed then. sparingly.If you are going to put them in larger containers do it now and dont worry if you loos a little of that soil in the process then don't feed them anything. Try some Gardener and Bloom soil check out the great price of $6.00 for 2 cubic feet. See composted ingredients in this soil on line cool organic stuff. packaged in Oregon.

Is this the overall consensus? Bueller? Bueller?

I have to disagree -- I think a flush is in order, but I've never grown in FFOF. I can't imagine the plants need nutes. Are you sure your PH is on?