Some people sware by that light cycle to fatten up buds, seems to work for them. Also, that 600w has almost twice the lumen output as a 400w so what is better is not even really a question, the only real concern should be weather or not you can control the heat with the 600w, because that is definetly what you want to use.
What kind of strain are you growing?
Adieu
BlueBear Reviewed by BlueBear on . 400 WATTS OR 600? WHICH BULB IS THE BEST FOR FLOWERING 400 W OR 600 ? Rating: 5