Only one I ever had trouble with was Astrenia stars. Anything that gets to far of a lead can cause big issues. Consider what there taking out of the system and its effects as well as a natural predator possibly. Harlequin tusk fish would devour em. many other non reef safe wrasse's probably would as well maybe.
My Astrenia star fish exploded after there years of safe levels, ate all the normals foods they cool find then devoured all my coraline algae off of everything, caused a alk spike and mag spike, then a huge nitrate spike. Then after tons of siphoning, I found a harlequin shrimp that made it thru my QT process and began the slaughter and rebalance of my system after the ALK up swing from no more coraline using it up. Everything has cause n effect in a reef tank. Be weary.... what there eating will need to be eating by something else and what goes in comes out as nitrate and phosphate. So expect needing extra WC till there under control compared to before the explosion possiblly.
