hps 600 watt creates 65000 lumens as to a t5 creates 40000.. so if like me u get 6 t5 2' bulbs at each end thats 24000.. add that 2 forty and u get 64000 lumens ... u can easily save $600 dollars a year on electric running t5.. plus u can run mutiple lights on one plug because of low power needed... this is what i plan on doing in the grow cab u suggested.. that way the ones on the side can be mounted as they grow to penetrate from each end into the canopy.... think of it like this a hps bulb is at one centeral point.. so when the light leaves the bulb it travels in outward direction loosing strength as it travels... but a t5 is suspended above with 4 ft long tubes that let light travel evenly down... out a little but mostly down.. thats y the plants on that post are so damn bushy.. Just make sure to get the warm bulbs!!! And also these damn bulbs can touch ur buds!! with no heat trouble! believe it! im a believer now 2.. t5 is less power, more money, but saved in a couple seasons, holds lumens power longer, nearly heat less, and light can be smashed right up to your plants.. buds can touch! peace