I run my lights 24/7 on my autos as well. I do however own a dimmable ballast with wattage adjustments I can run a 400 watt 10,000k RATED MH bulb in my 600 watt ballast set to the 400 watt setting. I chose to change bulbs to a lower wattage rather then just turning down the ballast using a 600 watt bulb I do this out of spectrum concerns. Still, 400 watts is 200 watts less than 600 so I guess I shave money off the bill anyway. I think the early stages of plant does not require the full 600 watts at least when vegetating. The cool tube fixture lets me use light closer to plant anyway, Heat is not a problem at least in my 2 FOOT BY 4 FOOT set up. When its flower time I change my bulb out to a full 600 watt HPS lamp for the finish. WITH PRACTICE AND MANY YEARS I WILL BECOME AS GOOD AT THIS AS GREEN