Lime green leaves

Hello fellow growers out there.
I am still a newbie and hope I can gain some knowledge here.
3rd indoor grow.
5 Plants (3 autos in back (Lambs Breath) & 2 fems up front (Acapulco Gold)
4x4x7 tent
Mars Hydro lights, 4 inch intake & exhaust.
Fox Farm soil & nutrients.
Back left auto has lighter leaves than the other girls.
Any thoughts and tips will be greatly appreciated.

The back left one looks normal colored over all, it’s getting optimum levels of N while the others are getting a tad more then optimum of N, making them darker. They all look good to me.

Thanks for the help. Thought it might be the case but always learning.
Take care!!