i wish there was some kind of indicator on the lights that say when the bulbs need to be changed, like how there is a battery that has this little bar on the side that shows up when you put your fingers on the dots. like batteries you don't really noctice the decline in power and you cannot be totally sure when its about time to replace them, i mean some people do the minimun ammount of light time a day, others leave them on longer (i have been known to leave them on from 11am to 12 am so i can enjoy my tanks while i am here at home, but if i am at class they get turned on from 5pm to 12am)