depending the bulb/fixture/duration of light per day, the general rule of thumb seems to be 1year - 18months is when you need to replace the bulbs.
some people wait until random algae starts to grow when everything was going well until then (hence my purchase of this fixture...i was one of those people.lol)
everything seems to love the light, its not over powering anything. if i got the ray 2, then that would be some serious power/brightness.
fish are happy, and plants are happy.
i'm only rocking amazon swords, wisteria and an ozelot sword.
a t5ho set up will provide visually brighter set up b/c of the much wider spread.
but this led is more focused light and therefore cause some darker shades near the upper edges of the tank.