Well, the yield is usually representative of how many lumens per square foot you are getting. I could have 40 plants in there, but if only 29 are getting good lumens, will the extra 11 increase my yield a whole bunch? Probably not. In general you are supposed to get a pound per 1000 watt lamp, however I figured since it was my first time I would get less than that. Know what I mean? Thanks for the compliments though guys