Hi there, im new to the forum and i just had some questions about what is the most efficient filtration for my tank. Im changing my reef over to a predator tank, but i am keeping a couple mushrooms and a couple simple soft corals in there aswell. I have a 180 g tank with a 75 g sump. Right now i just have a 6 inch deep sandbed in my sump with about 30lbs of live rock, and a protein skimmer. I have about 200lbs of rock in the display tank aswell. I plan to have 2 sharks, a small ray, 2 groupers, a goatfish, and i also have a blue chin trigger pair. Should i get rid of the sand? Replace with bio balls? Or canister filter on the side? Any suggestions would he great. I know all about the requirments for rays and sharks and the tank will be upgraded. I also wanted to know if your able to over skim a tank, the skimmer im getting is good up to 350gallons. Thanks in advance.