All my older systems all ran real reef rock, Fuji, Tonga whatever I could get and looked full of stuff... this current system I used most of that rock, but it was dry for a few years and filled in with dry florida rock.. my first year with this tank was the worst ever, fought coral deaths, crazy algaes and cyano, a bacterial bloom. My fish got bacterial infections. It was crazy. I honestly attribute almost all of it to the fact that I used all dried clean rock.. not that I'm over 3 years in it's pretty much good, and I'm glad I was able to manage to keep alot of pests out. But I dont know if I'd do it this way again. Theres alot we dont know and understand about the micro biologicals and their specific impact on corals and fish in a closed system. But I believe, like everything else we've learned in the last 20 years (we've truely have come light years from where we were in the 90s) that the next 20 years will really be some true scientific backing to our anecdotal knowledge. Bc we may be corals last chance on this planet.