Room temp 75-82 r/h 60 water temp 68 dwc seedlings in jiffy pods surrounded by hydroton . 3 weeks old from first leaves. 90 ppm current culture veg Nutes. Ph ranging from 6.5 to 5.5 currently 6.2. Fresh res change. Seems to be spreading still.
The yellowing and necrosis looks like a Mg or K deficiency. They look hungry. I would up the nutrients and keep the PH below 6.2 with a target of 5.8. Add a little cal magic as well, especially if you are running ro water
