You could be experiencing nute lock out. Is water getting sucked and nutes left behind making the PPM go even higher? Happened to me when my roots grew down to the plate and I didn't check run off for 2wks and ppm was 8500 in 200ml of water. Have pics up on hydro diary wk 7-8. Also using that many nutes even if you can ppm that low they cause lock out. I've read a lot about DWC. And your ppm couldn't be that low that's like tap water ppm buddy. Using 1ml/l of some of the nutes u have would set ppm at 400. I mix 13 bottles of nutes and I lowest I could get was 800. I truly think you drop a lot of your nutes. You have a lot that are very sim and mixing even 4-5 together you constantly watch the PPM, and make sure it doesn't get nute lock. Flowering plants that look that good are feeding off 9-1400ppm are u sure EC?