What are the dimensions of the room? 1.5 square metres or 1.5m on each side? Neither way equates to 50sq ft, I'm just wondering where you got this figure from.
If it is 50sq ft, then a single 400w is nowhere near enough. Optimum light levels are 7-10,000 lumens per sq ft, so you are looking between 6-9sq ft. Plants will grow with 3000 lumens/sq ft but you'll be much more impressed if you can give them more.

__________________
Originally Posted by ceestyle
Don't be a martyr wasting $100 or more on CFLs to prove they're inferior for flowering pot.