yah, i was talking to the dude at my local hydro store, and he said that one should have atleast a 3x3 foot area for a 400 watter, and i'm like right on the border line of that size, so i'm still on the fence about going any bigger honestly.. i think that if i got a better handle on my ventilation system, i could pull off the the four hundred, but untill then, i'm gonna stick with the 250.. my buddy mindmelted whom you see stop by my journal once in awhile pulled a lil over 19 o's off of one plant under a 250, so good yeilds are possible with one, lol.. just gotta get my sh$t together some more is all really..