Agree!!Go for it. For me that's the time when the plants really start to put on weight so why not bump it up to 600w.
Multiple strains..........Do yourself a favor USE THAT 600!!!!!!!!.peacethanks for the replies im running 6 different strains but there all around a 9 week finishing but i like to leave them an extra week.. il just have to watch the temps with the 600 until my cooltube comes...il be mounting the cooltube to my adjustawing reflector for max light coverage with little heat..
Not if you have adequate ventilation.my tent is 1.6m l x 0.6m w x 1.6m h ... i fink if i had my 400 and the 600 the heat would be too much..is 1000w overkill for my grow area?