I just built a new grow room for flowering, dem. are 4x5x7, in feet. I can't decide on how much light to use. I was thinking 2 400's, or 2 600's or maybe even 1 1000. I can probably fit 10 plants in the new room. I know 2 600's and 1 1000 would be better but would i be using more electricity for no reason when 2 400's would work great?