my leaves are turning yellow???

my plants are in a home made hydro system. with aretor and grow nutes. what could be causing slow growth and yellow leaves??

alf

Need more info bro..

and pics would be helpful remember pictures speak a thousand words lol.

im an outdoors man lol and that happens too me to mostly the bottom nodes right i haven't figured it out its nothing too worry aboutt though im almost sure

HEY IM NEW TO THIS FORUM THING ,I JUST STARTED THIS CLOSET GROW I STARTED THREE PPP FEM PLANTS AND THE OTHER TWO ARE UNKOWNS IM VEGGING THEM UNDER 400 WATT MH GROWBRIGHT JUST WANTED TO TELL ME WHAT YOU THINK AND WHAT ELSE I CAN DO TO MAKE MY GROW BETTER ..