Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
You are right to question the interaction between dechlor and test kits. Safest is to wait 24+ hours after using dechlor to get a more accurate ammonia test.
Yes, you have disturbed the bacteria population, probably reduced it somewhat.
Since it seems you are showing only a very small trace of ammonia I think it is not a serious problem, and the tank is just going through a very small mini cycle.
Do you have a test for NO2?
When the bacteria are compromised they cannot remove all the ammonia that is produced by the fish and decomposing matter in the tank. Removing the debris and feeding the fish less (especially less high protein food) will help.
The ammonia removing bacteria recover fairly fast, though, so a day or so of a minor spike might be all you see.
Ammonia burns the fish gills and tender tissues. But if the pH of the water is less than 7 more of the ammonia is in the form of ammonium (NH4+) which is less toxic. Do enough water changes to keep the ammonia under .25ppm for most fish.
When the bacteria population is compromised the nitrite removing bacteria are slower to grow back. They may not be able to handle the nitrite produced by the first population for several days or a week. It is common to see a lingering trace of nitrite even after the ammonia spike has subsided.
Nitrite enters the fish blood and makes it so the blood cannot carry oxygen very well. You can look up Methemglobinemia for more details. Add the word 'fish' for the best search results.
Add salt to the tank at the rate of 1 teaspoon per 20 gallons. This is a very low level, well tolerated by plants and sensitive fish. The chloride from the salt is protective, reducing the amount of nitrite that crosses the gills. Do enough water changes to keep the nitrite under 1 ppm for most fish. Add only enough salt to replace what you have removed for the water change (ie: a 5 gallon water change would get 1/4 tsp of salt). When NO2 no longer shows up on the test, you can stop adding salt, and regular water changes will remove it. Other sources of chlorides can do this, too, in case you did not want to add salt. You will have to research the dosing, though.
Either of these (ammonia or nitrite) in the water will make the fish act like they are not getting enough oxygen. Burned gill tissue or blood that cannot carry oxygen so well both can make the fish lethargic, they may hover just under the surface (water has higher oxygen level) or lower in the tank (less work to stay there). They may show increased gill action.
Doing water changes to reduce the ammonia and nitrite levels is removing the food the bacteria need, but is saving the fish. I do not think it will really slow the bacteria recovery, though. The bacteria population is already really close to what you need.
Other ways to boost the recovery:
~Make sure the plants are thriving. Higher light, CO2, fertilizer (but no nitrogen) will make the plants metabolize quicker, so use more nitrogen. Plants take in all the forms of nitrogen we are discussing.
~Reduce the amount of nitrogen entering the tank. Low protein fish food, for example.
~Increase the bacteria population by adding a product that contains Nitrospira species of bacteria. These are the actual species you want to have in the tank. Nitrospira is the nitrite removing species that is the slowest to recover.