u will have a shoter plant but clser nodes thats really about it oh yeah not to forget the high eletric bill.... i do 18/6 n use liquid light n average 6 inches a day.... i see how much they grow every day in vegg... n i use a couple 1000's n my room so i dont need to go 24/0 n when u turn off the light's for a day your plant will grow like shit cause it thinks it's gonna die... thats a trick to try... but do it right b4 bloom it will reset your plants internal clock