I’ve had 2 primes since the first model 5yrs ago above a 50 breeder mixed reef w/ beginner sps (birdsnests, stylos) midway up (9 inches above barebottom, spaced about 8 inches from either side end, and 5 inches above rim of the tank. Supplemented by 2T5 bulb fixture On tank mount 3 inches above rim. Grow corals without problems. Still have one original fixture from 5 yrs ago, replaced the other that died w/ prime HD 1 1/2 yrs ago, and have had no complaints since. For a smallish reef these lights can’t be beat for value and ease of use via myAI app. Running AB+ profile at 60% uv/blues, 4% green/deep red, and 19% white for 9hrs w/ 1 hr ramp up/down. I think the AI ecotech merger has helped push AI lights to a higher level at a faster rate since these fixtures now all share similar technology. Had one fixture’s fan die and was sent a replacement free of charge just out of warranty.