To be fair, I think the 50,000 hours for LEDs was a number that came up regarding LEDs a long time before they were tailored for the aquarium hobby and people have just run with it as a baseline. Too many factors to determine how long they will last. I don't really expect them to last that long, but if they do, great. It's kind of like saying a Honda will go for 300,000 miles. Yes, it can, but that all depends on your usage and maintenance. I plan to build newer, more efficient, and fuller spectrum units in that time frame.