I posted this in the diagnosis/discussion section this morning and haven't gotten any responses... I know this may not be exactly an emergency, but I lost a fish just two months ago to ammonia so I'm really scared about this one.
I just set up a new tank last month -- 10 gallons with a 90gph Whisper filter, an airstone, and a gargoyle that blows bubbles (so lots of aeration). In the tank is one very small but rapidly-growing goldfish.
Yesterday I checked the water with my Jungle multi-test quick strip. The hardness, alkalinity, and pH were all exactly in the middle, right where I want them, but both the nitrate and nitrite levels were off the chart on the "dangerous" end. I didn't have more than a gallon of room-temperature settled water on hand, so I did what I could. I changed out 2 gallons, using a second gallon of approximately room-temperature tap water. I also added a teaspoon (or a bit more... I approximated) of Amquel Plus to the tank directly. Last night I checked the water levels again and both Nitrate and Nitrite were still high, so I added charcoal back into the filter (which I haven't been using) in the hope that it would help lower the chemical levels.
This morning, the Nitrate level is a bit lower... probably about 160ppm or so, so still "dangerous." The Nitrite levels are still off the chart, so more than 10ppm.
Now I'm not sure what to do. Should I change out more water? I have 1 gallon at room temperature. Should I add more Amquel? I'm scared to add more because 1 teaspoon is the recommended level for a ten-gallon tank.
The fish, meanwhile, is perky and happy and swimming normally -- no weird behavior and no bottom-sitting or anything.