High nitrite and nitrates

Question
Approx. 5 weeks
55 gallon
2 kissing gourami
1 dwarf gourami
2 sword tails
2 silver dollars
1 pictus catfish
rena filstar xp2
ammonia 0
nitrite 2.0
nitrate 40
ph 7.4
Hi
We had our tank going for about 2 weeks had good readings.
Added a molly that developed cotton mouth we treated the whole tank which I am sure wipped every thing out.we havd been doing 10-15% water changes. We were told by a lfs not to do any water changes and add stability to the tank till nitrites went down than do 10% water changes every week. We have been doing this for over a week and nothing is changing.  Is this the way we should do it

Answer
Hi Ronnie;

The fish store is quite wrong about this situation I'm afraid. They also sold you way too many fish to get it started safely. I'm so sorry to hear you were misinformed.

There should only be one inch of fish per ten gallons until it gets through the break-in period of 6 weeks or so. That means about 5 or 6 small fish for your 55 gallon. The readings were fine for two weeks because that's how the process goes. After two weeks of fish putting waste in there, toxins rise in every new tank. It's just a matter of how high they go. Water changes during the break-in period are essential if the ammonia and nitrites get up to a toxic level. Otherwise, as you have experienced, the fish will get sick and die. With way too many fish in there the toxins have risen to very deadly levels. You should change 25% daily as needed. The nitrites will drop very soon because the ammonia is now gone and nitrates are elevated. Elevated nitrates is a very good sign that there is plenty of beneficial bacteria getting established in there. It is okay for nitrate to be up to 40 ppm. Partial water changes keeps it low. Nitrate is the end result of your aquarium's biological filtration process. Here's how it goes;
The fish make waste (ammonia), the bacteria eats the waste and turns it into nitrite.
More types of bacteria eat the nitrite and turn it into nitrate.
The nitrate is removed by partial water changes.

Ammonia and nitrite should be zero once it gets fully established. Maintain the aquarium with weekly 25% changes and a gravel vacuuming so the level of nitrate stays below 40 ppm.

Products such as 'stability' really are a waste of money. If the product works as the manufacturer says it does, you would not be having these problems. I have personally used other brands of this kind of product and they simply do not work. Like I said already, if they did work, you would not have dead fish and high nitrites. The break-in period would have been faster and less traumatic for all of you.

Here is a link to my article on new tanks to help you understand more about what the fish store SHOULD have told you;

http://www.xanga.com/Expert_Fish_Help

At Your Service;
Chris Robbins