need advise

web cant decide what room to set up the flowering room we have 2 choices, a 10x10 or a 10x20. we r going to use 4 1000watt hps. right now we r thinking of doing 20 plants at a time. is the extra space needed. will it let us put in more plants, how many plants would u guys recommend for the 4 1000w hps concidering the space

man 4x 1000w is some serious light output, I do 10 plants in a 2.5x3x5ft tent I built and I only use CFL's you could prolly stack a bunch in there if you use LST or SoG or Scrog. If you plan on super cropping you'll have to put fewer due to the fact that they get so wide.