i have noticed that most electronic ballast are dimmable however, most bulbs are not dimmable. in fact most bulb manufactrurers do not reccomend overdriving or underdriving the bulbs ? i just bought a new hps bulb and right on the box it says to only drive the bulb at the recommended wattage and that it can cause premature wear out of the bulb and a possible fire hazzard. even hortilux recommends on there website to run the bulb at the proper wattage. are all these new electronic ballasts that are dimmable giving us growers bad info ??