Question about roots

Is it bad if the roots are browning a little in a hydro setup? When my plants just started out the roots were really white. The container is closed and i'm using half the prescribed nuts. Is that nut burn?

I DO NOT GROW HYDRO OR KNOW MUCH ABOUT IT...

...but brown roots sounds like rot to me. Does any light hit the roots? What temp is the water? Do you have an airstone in the water? Have you tried peroxide?

Someone who knows hydro might help you out, might also be nothing.

Follow up: How long do your roots spend completely submerged? If it is too long they will get slimy/brown.

The roots are in water constantly. I think they need to be. I have 2 airstones. Maybe I need to flush the system and just run fresh water through.