400 watt set up with fans and all will increase your energy bill by 40-60 dollars a month..just depends on your rates. I ran a 400 and it increasead mine by about 56 dollars with a small fan. You can run them at night to get better rates from your company too, but then you have to worry about light leaks in the daytime.
Forwhat420 Reviewed by Forwhat420 on . College Newbie... First Grow. I have a bunch of CFL's and a 400 metal halide lamp but only a very small space (big enough for 3-4 mature plants at most). I am also wondering about the energy consumption of the MH lamp, I'm not really looking for a spike in the electric bill. So here are my 2 questions. Will a MH lamp be too hot for a space in one of those behind the stairs closets? And, Will a MH lamp use much more energy then the CFL's? Rating: 5