My little girls are sick :( need help fast

[Zerocalcare]

I'm growing in coco (Canna), Mammoth 120x120x200cm, 2x 400w Roleadro COB LED, Critical+ 2.0 (Dinafem), 27/18°C, 45% humidity.
Started from seed with 1ml/L of GHE Flora Coco Grow, water was @*7.5ph but I didn't have the necessary instrumentation to test it.
After 10 days, they started to appear sick (small twisting in the leaves). I first thought it was the temp so I've turned the fans in/out on. Nothing. Distance between lights/plants: also if they're leds, now they're 1m away.
Then, after 10 days more, deficiencies all over the place.
Tested water ph, flush with just water @*6ph to stabilize ph in the coco.

Still no signs of recovery.
Temps sometimes goes up to 30/32°C (shitty place).

What to do?

 

[stucrew]

CalMag?

CalMag?

One of the first things I learned about growing in Coco is to use CalMag 5ml per gallon of water. The coco will grab calcium and hold it so you need the extra. Also, the twisting of the leves is probably from the ph being way off. You want the ph between 5.6-6.2 I try to stick at ph of 6, seems to be the best in my flood and drain system. Do these and keep your water temp below 70f and they will likely recover well. Oh, and your coco looks dry. It is better to saturate it and let it drain, otherwise you will get salt buildup in it. Read up the info in Joes guide to sick plants https://www.icmag.com/ic/showthread.php?t=231387 BIG, BIG source of help for your plants. Hope you have smooth sailing from here on out.