ok so this is my second time growing first time on here

now problem is that my plant is turning yellow but not sure why im using aeroponics and im constantly got the ph around 5.5-6.0 and and im using GH florabloom for nutes i added 1 tsp of nutes and now im not sure what im doing wrong im growing 3 Super lemon haze and 1 afghan kush plant the afghan is fine but the SLH plants are realy delicate so im worried is going on and i dont even know can someone plz help its in da first pic btw and those 2 brown leaves are gone too but that color is still there