Robertsanswered grow question 4 years ago I believe this falls into the other answer I gave. Since it was on every plant in some degree is why I felt it was ph problems. The plant veins turn red when magnesium deficiency is present. Just if your roots are locked out because of ph then any deficiency can show up really. Always use a calibrated digital ph pen. Good luck 🌲🌲🌲👊