In my experience 18/6 was better 24/0 just made me have to water more frequently but there was a major difference every time i looked at my grow. But after several days the plant just stopped showing dramatic changes. I dont know if this is correct but i read somewhere, i think on RIU that 18/6 is for root and leaf growth and 24/0 is for leaf. But if you choose to do 24/0 i suggest you do it on the weekend. Why you ask, maybe its just me but i treat my plants like humans/famil/friends. They work hard all week 18/6 then on the weekend they party hard 24/0. In my experience the switching between the two light cycles 18/6 and 24/0 causes a major growth spurt.