I've had the ATI sunpower dimmable for over a year now and love it. I did have to replace two of the three ballasts. I believe that the cause was strange power surges, coupled with a faulty surge protector that the light was plugged into. The support from reefgeeks was awesome and in both cases they sent a replacement immediately. I haven't had an issue with the light since. It really does a great job by slowly bringing the reef to life in the morning, and conversely slowly quieting all the fish at night.