Why does my saltwater fishtank get cloudy everyweek?

My tank has been set up and running for about 2 months, its 150 gallons with one cancaster filter and two of the ones that hang on the back. I also have 2 powerheads that always keep the water moving. I have about 100lbs of live rock along with 3 clowns 1 puffer 1 starfish, a snowflake eel and some hermit . Why does it start to cloud up after one week. It seems fine when I take out about 25 gallons for my water change but then after a few days it gets cloudy again, why is this?