Slightly elevated nitrites

Jun 6, 2012
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Tested the nitrites this morning in my indoor tank. I've had it set up for about 3 weeks now. This tank is going to be used as my hospital tank incase one of my koi get sick. It's a 75 gal.aquarium with a 55 gallon blue drum where the filtrations is done. We have two filter systems set up for this, the main one uses a 3100gph pump which goes to the 55 gallon with bio balls and blue and gray matla for filtration and the 2nd is a small cascade (300) pump and filter that came with the aquarium. I also have an aerator with two lines running into the aquarium. Four days ago I brought in 3 of my "least favorite" offspring from last spring which are about 3 inches long. I noticed one laying on the bottom not moving much at all. The other two seemed fine. Water test showed nitrites around .10 -. 15 and the Ammonia was .10. I did a 20% water change last night. (we have a second 55 gallon barrel set up with dechlorinated water ready at any time for water changes). I did a water test this morning ammonia was 0 and the nitrites was still .10 - .15. I have read Salt will bring down the nitrite level. My question is should I use salt at this point or just let the bio catchup? By the way the fish with clamped fins laying on the bottom died :( the other two still seem fine.


True friends just call me Larkin
Mar 23, 2011
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Hammond LA USA
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It appears your going through a cycling process, which by the time frame posted is right on schedule. I would continue doing partial water changes every few days until you reach a balance. salt really isn't going to help with this for the most part. If you are feeding the fish during this period cut your feeding amount down by 50%. If your going to add anything at this point an ammonia locking agent or ammonia absorption product may help In the assistance of reducing the readings some. During this process it is best not to disturb the BIO material as it is starting to grow the bacteria, If you have a pre-filter that catches bigger debris before going to the Bio section of the filter it's a good idea to clean it on a regular basis so as not to contribute more waste for the Bio chamber to breakdown.
Jul 2, 2012
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Cape Cod, MA
Aww, sorry you lost one.

I dont have enough filtration/water chemistry experience to be of help, as honestly, I am confused as you would lose one so fast. You want ammonia and nitrites at zero, but these levels shouldnt kill a healthy fish so fast. Where did the water for the tank come from? an existing pond or the tap? You certainly are not over crowded for a tank of that size... thinking other contaminants? oxygen? issue with the filtration? I dont know. I have a 55 gallon tank running here that is down to 12 fish in the 2-3" size (as they grow, we move them)... Our tank doesnt have a complicated filter, just 4 aquarium filters...

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