I can never get the PPM's to those high of numbers. I believe it has to do with air, I run at half the recommended dosage of nutes and have better luck. Pretty big air pumps come with cch2o systems.400-500 ppm just seems really high to me. I calculate on the 700 scale so maybe that’s part of it. Generally at my other sites I can start at 150-200 ppm and the plants are lush and healthy up until a foot or two tall. 400-500 would usually lock the plants out.
I’ve been doing Rdwc for about ten years. Hundreds of successful harvests.