Saltwater Tank Is Cloudy?

Sounds like a nice tank! I would love to know why you are replacing the ceramic rings every 6 weeks. Fair enough replacing the carbon bags, but the ceramic rings as well? They are designed to provide surface area for the the bacteria to grow on to break down fish waste. Cloudiness in the water can usually be ociated with a build up of organic nutrients, i would go as far as to say that this time changing the ceramic noodles just tipped the balance of bacteria in your tank enough for the worst to happen. Test the water and make sure you have no ammonia and nitrite. If you dont have test kits, BUY SOME. There is no way physically possible to keep a SW tank without Ammonia, Nitrite, Nitrate, pH and salinity tests when you are just begining. Be careful if you do have a pH or ammonia problem your yellow tang may get whitespot as a result. Would suggest another 15% change today and every day until cloudiness disappears - when it does you know you have restored the bacterial balance. Only feed very little for the next week or so aswell!