I use 1000 watt hps on low (60%) for the first 3 weeks of flower. Then after the first flush at 4 weeks I switch the bulb to a 600 watt hps at 100% for 3 weeks and let them finish back on the 1000 watt slowly building up to "super lumens" (110%) The Internet is full of arguments for smaller wattage claiming it doesn't matter after 600 watts and it's just more expensive. In my commercial experience I have found the yields are far bigger with a 1000 watts throughout the bloom versus a 600 watt room. These were 92 plants per room so the numbers really stood out at about a 30% difference. The down side to huge yields is that environmental conditions become a hasstle. The room with 600 watt bulbs was dense but not as big but the maintenence was next to nothing. For a home grow where you have less plants you have more time to deal with humidity being trapped in between the nug and the stalk and environmental conditions are much easier to control. Sent from my SPH-L720 using Grasscity Forum mobile app