I have a 6x6x6 room, im running a 400 hps over it now, I was wonder if I add 2 150 watt lights 2200 lumens if it would help the grow. also I have 6 plants in 5 gal buckets with 2" of peat rocks on the bottow than a mix of MG and peat moss. Do I need drainage holes? any tips would be awesome
To answer your question simply, YES. Honestly in a 6×6×6 400 watts isn't going to be nearly enough, depending on how big you want your yield to be.
But if you are wanting to maximize yield for your space, I recommend getting a 1000w hps. They really would only need that much power during flower, so if you had a dimmable ballast you could run it at like 400 during veg and then kick it up to 1000 when you start 12/12.
If a thousand watt isn't an option or in your budget then the cfls would help. There's an old saying, "watts is weight". 90% of the people that you will find on here who are having a problem with loose and airy buds, are having that problem bc they don't have enough light (usually they are using cfls).
Remember, cfls don't have much penetrating power. So if you go with those then keep them as close to your plants as possible, preferably 1-2" from the plant. But if you can get a 1000w in there, with a big hood that will spread the light, then you could easily have a 2 pound harvest in that space.