I run mine from 745am to 645 pm for 11 hours with VhO actinics 45 minutes before and after.My growth has been incredible. I know i cut down the life of my bulb but this way they get alittle more sunlight and i can watch them alittle longer too. Plus if you think about it the Sun doesnt turn on and shut off 10-6. I always thought that you should try to synthesize nature.