Hi, so either you have issues with the light, which I don't really suspect, or it could be a nutrient lockout due to the wrong pH value. Check the runoff to see if everything is okay; if the values are all correct, pH between 5.8 and 6.5 and the EC value under 2, then check your DLI value, which should be between 35 and 40. But like I said, it’s more likely to be related to the pH value.