I know that this happens a lot for many people, but I am having an intermittent cloudy water problem in my tank. There is a number of reasons why this is puzzling to me though. One of which is that normally, my tank water is pretty crystal clear. I have a 20 gallon tank which is being filtered by a 55 gallon marineland emperor set up. I change my water at least once a month (which is all it typically needs with this size filter). I also do not over feed my fish, so I do not see this being a problem either. However, sometimes after I change my water I get a severe cloudiness problem for a week or two before it clears up. This doesn't happen all the time, just every once in a while, but when it does happen, like I said it takes a while for it to clear up. Any suggestions on where this is coming from? Input would be great. Thanks for your help!