maybe mold? maybe not?

My plant looks healthy above ground but i looked at the roots and saw this white stuff should i be concerned? How can i fix this.the browning of the roots is just residue from the nutes im using and medium particles.

I have no idea what you are referring to with your question. What I would like to know is, WTF are you using for medium in those net pots and running a hydro setup? Looks like dirt to me. Bad idea.