Roots getting dark after nute change.

I'm not sure I understand. What is gross? Are you seeing something wrong? What is Hygrozym and it's purpose?

When this happened to me my first time in rdwc, I killed everything with h202, waited a couple days for it to evaporate and then added hydroguard. Also lowered my chiller to 66. Worked very well for me.

Roots look a lot better. Hygrozym is just an enzyme product. Another "beneficial" additive if you need it. Hydroguard holds me down. I finished a grow with 85 degree water in a RDWC (70gals) with 3 weeks left without a water chiller.

Okay, so you guys are awesome now that I have added the hydro guard the problem didn't occur again when I did a rez change. Also, the plant seemed to get healthier and grow quite a bit faster. Thank you all so much. Only thing that I still can't figure out is why my leaves are cupping so bad.

you have to much humidity in the room get a hydrometer for 12 dollars on amazon and control it

Change your nutes line Advanced Nutes have a high salt content (you probably have sludge at the bottom of the res when it gets low. I use Canna line, but research for your self and find a line with low salt and good beneficial bacteria. When you add nutes it shouldn't cake up air stones, pumps, and stain roots.