ive been useing gravity for 4 months now. with excellent results.. as soon as i go into the 3rd week of flowering i start to add gravity. follow the directions and continue to use until your ready to flush. what i have seen as far as results. ive been raiseing white russian for about a year now. i was getting fingering and some whispy bud production. after useing gravity ive went from that to really solid rock hard buds. 4 sure im sold and will continue to use it.