please help me diagnose my sick plant *pics*

so im doing dwc and have 4 plants in a single res..so i dont think its the res mixture that is causing it. but im using half strenth gh 3 part. my ph is good and there under a 4ft 4 bulb t5. any advice would be greatly appreciated

anyone????

What are u using for calcium and magnesium ?

all i am using is the 3 part gen hydro nutes. but as one other there is the same strain and they are all in the same nutes idk how it could be a defic.