Goldfish dieseasse and maintaining

Question
Hi, Ron, I hope you might give us advice...
In September we got three gold fishes to my daughter. We bought also a tank of 50 Litres, solution of bacteria to ensure natural flora of the water and a filter. They told us that with those we could easily change the water of the tank only once a month. But, the water always gets too dirty, cloudy and by the end of each week smelly. Of course we change it once weekly in this case. What I am concerned about is that we may be miss something and can take proper care of those creatures. I was told by an expert at the shop that every time I change the water, I need to save some of the old water, to keep the bacteria, that I have to clean the filter with the old water as well and never wash it with tap water; I also had two types of solution to put into the water - one with the life bacteria and the other to remove the chlorine from the water. Well, in the beginning we had a very clear and clean tank and happy fishes, but then, by the 10th day it got cloudy and smelly again. And we also feed them with not too much food so it doesn't rot there. I don't know what to do any more. The latest news is that one of the fishes got a purple-white like a bubble spot above her eyes, on the forehead...I am afraid it is sick...Will appreciate your advice! Thank you very much! Stassie

Answer
Hi Stassie,
 The single most important thing to do for a fish tank is to change 25% of the water, once a week, every week.  I never add any of the bacteria solutions -- I think they are unnecessary -- and I keep about 100 fish tanks.  

 I clean the filter under the tap.  If your water has a LOT of chlorine in it, then don't do this but in most cases it is fine.  

 In the short term, I would change 25% of the water today, change another 25% tommorrow and 25% the next day.  That should clear it up and get rid of any smell. Do not add any bacteria solution.  

 After that, start the once a week 25% water change schedule and see how that works out. Be sure to never use any soap or detergent anywhere near your fish tank or in any of the stuff you use for the fish tank, e.g., water bucket etc.

-- Ron
  rcoleman@cichlidresearch.com
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