testudo i had many problems like this before, it seems like they are getting to much water, what i would do is give them high nitrogen for about 2 days with lots of light. It seems like your plants are stretching so i would also move the light closer if possible. A simple hand test from the canopy of your plants to your light shows you if the plant is to close to the light. If your hand is hot at top of canopy its to close. So simply give them very little water for two days. Then after that high in nitrogen. 24 hours of light.