i would remedy the underlying issues before adding anything to the res. ppm should be 600 imo, water and canopy temps need a drastic reduction. get on it and the roots will heal themselves
If you don't like the tea resolution like me then try a product from Dutch Master called Zone. It is primarily copper sulfate witch both have anti-pathogen/fungus properties. (Don't mix with tea as Zone is an indiscriminate killer of all microorganisms) Root rot is ultimately the responsibility of one of 3 fungus strains. Most common is Pythium ssp. (If you want to know more just ask. I'm an encyclopedia on pythium fungus. It took me the better part of a year to solve my issues) If you continue to have a more aggressive problem then there are more aggressive actions that can be taken. I have gone all the way to spending $550 for a quart of a very hard to find fungicide. I got away with using zone for 9+mo before seeing any resistance buildup. I am now alternating between Zone and 2 different targeted fungicides. Sent from my SAMSUNG-SGH-I337 using Grasscity Forum mobile app