what is this, nute burn? help

[rudituite]

hydro
water\feed gets pumped on table runs down an bak into tank
rockwool
2x 600w sodium
2 weeks grow then switched to 12/12 3 days ago,ph 5.8
ionic bloom, 0.6 on tester in tank

wat u think peeps?

[rudituite]

i had sum heat stress about 5 days ago when i switched second light on, the humidity went to 0 and leaves started to curl in so i switched off second light and highered the first 1