Hard to say. I had a "desperate" rdwc run several years back and nuked it with physian 20. Then benies.. the plants looked fine but didn't grow for like 3 weeks.
Look dude. Tystk and I do this shit for a living. And I'm not taking oh wow.. 10k watts. We are talking $150k + commercial build outs. My overhead is 20k a month so when she goes wrong.. it HURTS. It hurts REAL bad.
I currently have 96 5' tall plants, 55 2' plants and 55 small plants in DWC.
1. We never ever never let the water get above 67, ever. Typically it's 63-65.
2. We add 5 gallons of beneficial tea to our 200 gallon reservoirs twice a week.
3. We never use any kind of coco or dirt or whatever... it ALL has bugs in it.
4. New airstones every round. Yes, we buy 50 air stones a month
I have not seen root rot in about a year.