whats going on here

800 ppm 4 and a half weeks old, dwc. grow big hydro and big bloom.

you might have a PH problem.....

Do a flush now and see if it helps..

Check your PH and cut down the ppm's I think 800 on a 4 week old maybe a little too high for it.

flush it out

i've checked the ph. it's at a 6..and all the other plants seem to be fine. It's only on that plant..no others look like this.