it takes 5 250w HPS bulbs to equal the lumens of one 1000w HPS.

1000w HPS standard bulb 140,000 lumens

250 w HPS standard bulb 28,500 lumens

28,500 x 4 = 114,000 lumens you are 26,000 lumens short so add one more 250 w HPS and you are up to 142,500 lumens. You will spend more money for equipment and power cost as well. 250w HPS will not have the penetration so they will not cover the same area like 1000w HPS would.