Plants weaks!! Heap!!!

The plants was growing well for about 6 weeks, then this started to happen.
Its growing indoors, I nute them every sunday with MG about 200ml half strength. They are in a mix of potting soil, peat moss, vericulte, and perlite.
Can some one help plz.

You have a nutrient lock out.......either due to the soil or ph......need to flush with ph'd water imediately and then give your same nute solution after 24 2 days.

u fried that bitch

start again