need help

[Magoo2003]

I have some babies. 5 of them to be exact. 4 in rockwool cubes, and one in a 50/50 mix of perlite vermaculite. They are about 2.5in to 3 in tall. The 4 in cubes were doing well untill the other day. There roots are brownish and some leaves have discoloration. yellowish/dark greenish discoloration. They are in cubes on top of some hydroton rocks, in cups. I stopped giving them nuts yesterday. The other one started in rockwool but i moved it to perlite verm mix, it looks oks but is not really growing. What should i do? thanks

[Rusty Trichome]

Did you rinse the cubes before starting the grow? I don't use em, but have heard that they tend to be rather acidic. (I'm pretty sure it was the rockwool cubes) Don't know for sure tho.
But...if they are too acidic, can cause nutrient lock-out.