How long will it take for my 75 gal tank to look clear?

How long does it take for Marineland C360 canister to work where i can see my 75 gallon tank nice and crystal clear. I put it together for over 24 hrs ago and my tank is still a little mirkey. I have a freshwater tank with about 18 african cichlids in there. Please help me and tell me how long it could possibly take..thank you very much.