Electronic ballast run cooler and are more efficient than magnetic ballast. When new, most are 95% efficient whereas mag. are only 85%. In time though because of the heat from the mag. ballast they start to break down and over a few years they go from 85% down to 50% efficient. The heat from the ballast is wasted energy. There is one thing that most people don’t realize that there are lamps made for mag. ballast called probe start and lamps made for electronic called pulse start. Matching the right lamp to the right ballast can make your lamps burn brighter and last longer. I have been getting 18 months from my Reeflux lamps and electronic ballast with a 5% reduction in lamp brightness at the end of 18 months. I have done this with both 175w and 250w on two different tanks. As a matter of fact without a meter I could not tell the difference in the look. Before I close it takes 100 hours for MH to burn in. What that means is when you first start running your lamps they will be at there brightest after about two weeks before they start going in the other direction.