The downward curling leaves could be a sign of nitrogen toxicity. When plants receive too much nitrogen, they tend to develop very dark green, shiny leaves that curl or “claw” downward. Even if the EC is not extremely high, an unbalanced nutrient ratio with too much “Grow” or nitrogen-rich fertilizer can lead to this issue in DWC systems. To fix it, reduce the nitrogen input by lowering the Grow component or adjusting the nutrient mix to a more balanced ratio, and maintain a moderate EC around 1.0–1.1 while monitoring new growth.