Mars hydro

Im on my 3rd grow. Using 3 mars hydro 600 using biobizz (all of them) using half dose to not cause any over feeding. The girls are very happy.im using ro water with proper calmag ect. The lights are 18 inch is away from canopy as directed. Now I'm loosing my shit !!! Whay are my girls looking like this . Pic 1 and not this pic 2 .. ahhhhhhhhhh why so small!!!!? Thanks in advance. Pic 2 not mine sadly. Switching to flower next week.
 
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