What the hell is going on here?

delete this message

necrosis. or nute burn.. again.. lol

just kidding... seedlings and cuttings are sensitive to nutes. up to the point that their root system is fully developed. the curling leafs are the odvous sighn of nute burn. dial back the nutes a lil ways maybe half strength or so and ride it out. i urge you despite some crappy advice you may get do not flush your plants. hope u take my advice happy growin.

I see 2 problems, no mention of cal-mag and your using r/o
sealed room with no c02 supplement or fresh air in means stale air with 0 ppm of c02

your plants have to breath it looks like bad nute burn and ph issue im a soiless grower not a fan of hydro for this reason its less forgiving does the brand of nutes that "your friend" uses automatically buffer ph or is the water ph'd before and after ? the yellowing from the middle looks like it needs P

The nutrients are pH buffered by the company.

The leaves are not crispy at all, other than where they are totally dead. The leaves also feel softer than one generally likes.

then when then mixed properly there should be no ph issues its not buffering the amount of water your using because the solution is to weak prolly what the tech meant when he said it needed to be mixed full str

ive had them burn and lock out on me a couple times

I feel down stairs, now my ass hole hurts

i dont know if this is taboo but knowledge is power https://www.icmag.com/modules/Tutorials/PlantTrouble/Nietzsche.htm

my power cord caused me to death