A 400 watt hps will use about the same amount of electricity as a common desktop pc. Should not see that much difference in electric bill.
SAP420 Reviewed by SAP420 on . 400 Watt Growing in Apartment with Grow Tent??? Does anyone grow in an apartment that they live in? Do you use at least a 400 watt bulb? Please let me know if you think this would be fine (grow tent) and how much your light bill is usually monthly? Thanks. Rating: 5