your adding nutes without a ph meter?!?! your going to fuck your shit up son. nutrients are highly acidic to maintain product shelf life. once you add it to water it makes the water even more acidic causing your soil to become acidic. thats why your prolly going into lockout. the other 10 plants are eventually going to become like your problem plants. are they grown from seed? that maybe why the others are hanging in there more, because each seed has its own genetic makeup and can tolerate stress more than others can, but will eventually fack up if you continue. your problem really relies on your soil ph and the ph treated water you put into it. correct it and you should be fine. remember damaged leaves will never come back to norm. just look at the new growth