it wont be quite as efficient as a 1KW HPS, because thats about the best lumens/watt you can get in a light, BUT it is a SIGNIFICANT amount of lumens, and enough to get some decent weight... if you are a first time grower, and you have never set anything up like this, i would say you could get from 0-8oz dried... once you get it perfected, you could possibly get up to 14oz... about .4g/watt... if you do some advanced stuff, which requires more attention, like topping, FIM'ing, or screening - in a hydro system, you could get over .5g/watt - i've seen up to 1g/watt but that was in a small cabinet with a small hps and a screen - and probably run longer than 3 months.... I started with some shitty T12 flouros, anything can be done.