what nutes are you feeding them? what ec? ak47 is a very tough plant but i think uve got nitrogen burn here is a link to some plants effected by nitrogen burn, compare your plants with these if they have the same symptons then you know whats causing it http://www.google.co.uk/images?um=1...bis+nitrogen+burn&aq=f&aqi=&aql=&oq=&gs_rfai=