We have a 55 gal tank with an Aqueon 55/75 filter, 60+lbs of live rock, 3 sea urchins (initially tiny hitchhikers, thriving well, and very large now.) We are only about 5 months into this hobby...all of our fish are tank bred, we have 2 small clowns, a purple psuedo, a blue tang, a longnosed...