What is wrong with these plants. burn or diff??

they look a little burnt. have you recently upped the nutrients?

ide say nitigen defishent had my first crop do the same thing looks cool at first but no good add some nitrogen rich fert and it will recover in 3-4 days but those leafs are done will never heal, but your plants will be fine dont prune those until new leafs come in they be nice and dark green if you add nitrogen. most hydro nutes will require a nitro additive every two weeks or so. i use urine it all the rage and free delute 10:1 minimun and water with asap.