If you are running a 400, you are going to want to keep the plants VERY VERY short. 2 feet MAX... you would want to flower them as newly rooted clones.
Electric costs... you can calculate that yourself by loooking up your cost per kwh... and add at least an extra 10% for associated cooling costs. A big light needs big cooling.
stinkyattic Reviewed by stinkyattic on . Just starting to grow and need some help Hey :) We just joined this site because we have been moving around a lot and finally found somewhere stable to live. After growing outside and not being too successful, we are now trying to move to hydro. We want to grow anywhere between 4 and 6 plants at two feet tall. We wanted to know if a 250 hps or 400 hps would be needed. We kind of want to keep the electricity low but also want to maximize plant potential. Also we wanted to know if a 5-10-5 solution would be a good root stimulator. Rating: 5