Hey man not trying to hurt feelings at all but those roots are in bad shape. You should not have brown roots at all. Your roots should smell like a fresh cut potato. If you can easily squish a root in your fingers and they smash up easily then bingo, root rot which it looks you have. In one of the pics it looks like some of the flowers are starting to brown out and yellow a little. This is a good sign of root rot.
Also you mentioned using
Superthrive in Aero. That is a NO NO!!! Everyone I know that has used it in aero has had problems with roots.
The only time my roots look brown is cus I use H&G Roots Excellerator but the brown washes off.
I have never seen healthy roots that are brown when using the nutes you are using.
Do you have a water chiller for your setup? Can you please tell us the water temps in your hydro setup and res?
If it is root rot I know Roots Excellorator will help the rotted roots re grow. Best root stimulant on the market hands down.