If your nitrite level is 10, you really need to do a 90-100% water change. It won't affect the nitrifying bacteria because they live on surfaces, not in the water. High nitrite/ammonia is probably what's currently killing your dwarfs.
If your nitrite level is 10, you really need to do a 90-100% water change. It won't affect the nitrifying bacteria because they live on surfaces, not in the water. High nitrite/ammonia is probably what's currently killing your dwarfs.