water cloudiness, fin rot

Question
Hi,
 We have a question regarding the cloudiness of water and fin rot. We got our sons tank about two months ago, it is a small tank with only one oranda goldfish, it has a filter and an aerator, when we got the tank we let it run for a week without the fish. My questions are:
  The tank needs to be cleaned every third day as the water becomes dirty, but no matter what is done the water is never clear it is always cloudy. I have read that it is because of the bacterial bloom. What can we do to get the water clear.
  Recently the fish developed fin rot, it had bright red patch on tail, we have treated it with the melafix and salt, now that redness is gone but has whitish patch in its place and the fin looked raggedy, I can also see all the rays on its tail and body, she is not swimming as much as she used to she is mostly sitting at the bottom, can it be because the fin rot is because of the fungal infection and not bacterial, what else can we do to help it because the three day time of treating it with the melafix is up and she still doesn't look healthy and we don't want to loose her as she is my sons first fish.
  Thank you very much in advance.
Midhat.

Answer
The goldfish will mend... but it takes time.  Add beneficial bacteria to the water at twice the normal dose for the first time and then each time you change the water... once or more times per week... add bacteria at the normal dose level... this should help the water be clear.  If this does not work... then let me know and I will suggest some other things that you can try... .dave