question about lighting

lets say that you have a room thats 6.5 ft long 5 ft wide and 7 ft tall and you are using a 400W MH light, is that strong enough for the room? also will it affect yeild and quality if you use a MH light for flowering instead of a HPS?? I would appriciate as many opinions as possible. Thanks everyone!

I have an area that is 7lx6wx7h and a 1000w supersun hood. ive been told thats enough, barely.... a 1000w covers an area about 6x6, a 600w about 4x4. i would use the 400w MH to veg in a room about 3 1/2' X 3 1/2'. then get a 600 watter for a flower room about 4 1/2' X 4 1/2'. add reflective mylar to use all the light you have too.

how about instead of reflective mylar if you were to put some of those t5 lights right on the wall near the botoms of the plants where not as much light get through to?