i have 2 primes over a 24x24x20 cube and i think it's lacking light, although i don't have a par meter backing that statement up
most of my acro success is on my highest rock maybe 6" or so below the surface. and even then, success being stuff is alive and somewhat growing, not really what i'd call thriving. this is my first reef tank, though, so perhaps i'm messing something else up. i have spiked my alkalinity a couple of times so i'm sure the corals were less than pleased with that
there's a youtuber named J's reef that has a sps heavy tank under a bunch of primes, but idk what his growth is like. he had a video awhile back where he par tested and it was lower par than he thought, so he made his light schedule longer to compensate
honestly, if i was doing it all over, i'd go with something higher light or at least do a t5 hybrid with the prime or something. that's if you're wanting to go down the acro road. i have zero issues keeping non acro sps alive and growing