This section is designed to answer problems you might experience with your tank in which you dosed One & Only Nitrifying Bacteria. If none of the existing answers give you the solution to your problem, please email a description of your problem to us at

TROUBLESHOOTING for Dr. Tim’s One & Only Nitrifying Bacteria

I added One & Only and the next day the aquarium water was cloudy or milky

Cloudy water is not caused by nitrifying bacteria because they cannot multiply fast enough to reach a population level that would turn the water cloudy. Cloudy water is generally caused by a bloom of heterotrophic bacteria in response to elevated levels of organics in the water. This can be reduced by thoroughly washing the gravel, rock and other items before placing them in the aquarium. The best way to control cloudy water is to do a partial water change and limit feeding. The water will usually clear up after a day or two.

I added One & Only to my tank which already had high ammonia (nitrite) and the concentrations did not drop

If the ammonia or nitrite concentration in the aquarium is above 10 ppm (as nitrogen) or 10 mg/L-N, you should do a partial water change before adding One & Only. The reason is that these bacteria prefer low concentrations of ammonia/nitrite and can actually be inhibited by high levels of these chemicals. Thus, a tank which already has high ammonia (or nitrite) will not see results as fast as if you had added One & Only at the beginning. There are two solutions: 1) change water or 2) add more One & Only while reducing feeding until the situation resolves itself.