goldfish tank and nitrate levels

Question
I am a total novice with regards to fish and tanks, but here goes We won three goldfish at a carnival that came in a small container. Two quickly dies and the third lasted about three months. We decided that we should upgrade and went to a pet store to but a larger tank with a filter and another fish. WE set up the tank with no instructions from the store and unfortunately the new fish died after only 1 week. I did some research and bought a water testing kit. The Nitrite levels is extremely high and despite doing 25% water changes and adding Prime to reduce the Nitrite level, it remains at the top levels; all other levels, e.g., chlorine, pH, etc seem to be within the "safe" range. Any thoughts about what it happening or what I should do? I will feel terrible if I can not safe this little carnival fish that is a real fighter. Thank a bunch

Answer
Tina, I would like to know how large a tank you have. What you are going through is completely normal. It is commonally referred to as new tank syndrome. When you added you goldfish to the tank you added a ton of bacteria. This is good you need that to keep your tank healthy. The goldfish waste is ammonia. The bacteria then cycles it to nitrites , then to its least toxic form called nitrAtes. Golfish are notoriously dirty fish, but thats ok if you keep your tank clean. I wouldn't recommend NO more than 2 golfish for a 10 gallon tank. If your levels are too high try to do only 10% water changes and as least as possible right now while your tank is cycling down and creating its ecosystem. This will detoxify the water and keep your fish happy Don't lose hope just hang in there. Your tank is just trying to establish itself. I would recommend syphoning your rocks and changing your filter evey month ...If you din't know what a syphon is your local petshop has one and can explain how to use it. I would only add one fish at a time and wait a week between fish.  Tina