Ime(maybe 10 years of hydro/dwc) 200-400ppm veg and seedlings, 500-800 for flower. I grow big plants which has a pretty drastic effect on what the plant can take in dwc. The old romulan cut was the only plant o remember really needing over 1000 ppm in dwc early to mid flower, think it was up to 1400 or so for about a week before cutting back, but that bitch could run at fucking 2k in soil outdoors when it was big and loved it. Very unusual though. Ime most strains in most media would rather be at the low end of the feeding range than overfed by a long shot.
At this point I’m in coco, rockwool, and dwc, and I use dyna grow and veg plus bloom in their recommended amounts. Never over. If the plants look like they’re starting to get a little overfed, I’ll feed straight water for a day or two and that almost always solves the problem.
read your plants. They let you know what’s up