Fish Tank Cloudy Green

Cloudy Fish Tank!?!? Help Please!?
I have a 20 gal fish tank that has mixed breeds of fancy goldfish, a pleco, and two snails. It has an external power filter. For the past month its been extremely cloudy. This cloudiness doesnt appear to be algea because it isnt green its white. What is causing this and how can I fix this problem? Please help!
The main cause for this is probably overfeeding. Goldfish have to eat at least 2 times a day, not more than that, otherwise your water will be most of the time cloudy. Goldfish give a lot of waste and as a result of that your water becomes cloudy. Change water once a week, 20%.
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