Sure looks like it to me. You will notice a different odor from your roots when root rot starts. Unfortunately once you get it it will spread and infect other plants. I have tried everything & nothing kills it, most treatments only slow it down, I have not been able to kill it once it starts. My only advice is get it away from your other plants.
It is also possible it is the type of nutes you are using. Also do you use food grade peroxide in your res if your not you need to at 3ml per gallon of water when you add water and every other day half that dose. Also why do you have pieces of leaf material in your net pots? This has me believe you are not keeping a clean environment. Also I don't see many herring bone type pieces coming off of your roots which leads me to believe you are over watering
Is your system steril or do you use mycos. So many variables, What is your temp in the res? Sent from my SM-N920T using Grasscity Forum mobile app