Had a little hard time, i fim the yellowish one a bit too early. After that, i got oïdium on both my plants. Had to change the water, try to cure it. I destroyed few leaf trying to clean oïdium from them. I get through that infestation using milk (1/9) and spayer, but they got touched. After the res change i had water fluctuation i haven't noticed, that's probably the reason for the yellow coloring i guess.
Seems like new roots are growing, hopefully enough for a new start, hard time should be behind us for now.
Not trying to knock you or anything but I'm not sure what's going on here why does the water look like motor oil and why are your roots so dark and nasty looking I'm also doing my first dwc as well all home made . Very surprised plants are even standing. Yikes
Guess I missed a few pictures overall looks like you fixed something because its definitely starting to look better .I can see the potential and on a whole other note I'm not sure exactly what's being used but my friend did a dwc in his backyard shed using tap water 1 100w metal halide in Las Vegas summer so around 115 degrees o and using bag seeds from the early 2000s like over the border brick nasty weed seeds and that plant puts most peoples operations to shame I think people put way too much stuff in there grow. Hope this helps a bit wish i had pictures but they were taken and developed and been lost over time