He described the exact symptoms of underfed dwc. He stated his ppm was far lower than it should be at this age of the plant. Also we probably never heard back from him cause many of the above suggestions are all a recipe to make his situation worse. Here's a pic of a week three from seed sour tangie getting 700ppm and 300w of led draw in rdwc. If you aren't recirculating remember to stir your pots or all the good shit falls to the bottom. In 3 days I'm bumping this up to 900ppm cause its starting to go a bit limp already. But yes. Too high a water level and too little oxygen, and pithium can cause this too. Maintain cleanliness, ph, ppm and temps, but most of all, maintain vigilance.