well im running alot of 1000 watters and some of them are a year old and some people say change them out every year.Well there is no way in hell im going to spend thousands in new bulbs if there good .so i got a light meter,a good one not a grow store meter eather. I played with it some and man its nuts how much you will learn about light .one foot from the bulb is magic lummens three feet away .it ant shit.light 6 inches under the vert bulb is horable .