originally i had about 200lb in 150g. , but had alot of dead space. Eventually built up high nitrates and ridiculous amounts of red slime, bubble algae,and brown algae. All corals and fish died regardless of what we tried. Cleaned it all up and sold most of my live rock back to lfs. Right now i would guess about 75lbs. live rock. Bought new 50 gal. sump, ps and used old uv filter. I'm not sure what size return flow pump is... running 3 powerheads at the moment. Am afraid to put alot of lr in because of problems from before. I'm terrified of getting that algae problem again. "Fish guy not much help. Says he knows alot, but not much help. His answer for everything is dont feed so much and dont run lights so long. I feed 1/2 cube everyother day, divided between 2 tanks. Other tank is 95 gal. sw wave tank. I have been at this hobby for about 5 yrs... the last 3 battling algae.