for my next grow i will be useing a grow tent 120cm sq and 200cm tall i now a 600w is just right for th size of the tent but dont realy wana use all that leccy. so will a 400w be ok?
400 watt only cost 30 cents a day to run. a personal computer uses 35 cents a day. so a 400 watt hps costs $9.00 a month to run 2 would cost $18 a month very cheap and well worth it. dont be scared of the elec company seeing more useage and start asking questions. we live in a electric age so as long as u dont steal elec you will never be investigated.
hydro is right .... and to be honest 120 cm sq (which is about 48inches squared for us americans hehe) is a little tight even for the 400 watter. a 250watter would be just fine for this amount of grow space, although if you planned on growing more later i would get the 400watter. good luck
a 250w just right for a 2ft sq space a 400w is just right for a 3ft space a 600 is for a 4ft sq space