What's the expected lifespan of a T5 bulb? My light rig has six bulbs, two of which are actinic. The actinics run 7AM - 9PM, and the other four run 8AM - 8PM. They are not being overdriven to my knowledge (although I need to confirm that). The reason I ask is that I've got a few corals that are bleaching a little, and I can't find a chemical reason to explain it. I read something recently on RC saying it might be possible that my bulbs were getting too old and creating problems for the zoozanthellae, which would result in bleaching. Any thoughts?