Ammonia is an extremely toxic pollutant in aquariums that comes from decaying food, fish poop, or dead animals. A healthy aquarium should have no detectable ammonia in it. If your ammonia testing shows detectable amounts of ammonia, then it is in the context of one of three different situations. Here is how to decrease ammonia in each situation.

How To Decrease Ammonia In a New Aquarium
In new aquariums, less than a month old, it is normal for ammonia levels to be high. This is because natural living bacteria that make up the aquarium’s biological filtration have not yet colonized the rock, substrate, and filter media. If you have ammonia in a new aquarium, it should go away by simply waiting. If you want to speed up the process, you can add bacteria to the aquarium to help the natural biofilter establish itself. We recommend adding Brightwell Microbacter Start XLM. If you already have fish in your new aquarium and the ammonia levels are high, you can use water changes to keep them below 1 ppm. This will keep the ammonia from getting too dangerous for the fish but will leave enough ammonia for the natural biofilter to establish and eventually bring the levels down to zero.

How to Decrease Ammonia After a Catastrophic Event
If you have an aquarium long enough, you will experience some kind of aquarium catastrophe. It could be a large fish that died after a power outage, a child who dumps an entire jar of fish food into the tank, a large clam dying, or a big anemone getting sucked into a pump. In any of these situations there will be a large amount of ammonia introduced to the aquarium from dying animals or way too much food. The best way to solve this problem is by doing a large water change. Remove the food or dead animals so they stop producing ammonia, and drain out the ammonia-filled water and replace it with clean water. We normally recommend doing no more than a 50% water change at a time, but in a true emergency situation changing 70-80% of your water might be a good idea. The water is toxic, and it needs to come out. Make sure that the clean water is the same temperature and salinity as your aquarium to help reduce the stress on the animals and quickly perform the water change.

How to Solve a Chronic High Ammonia Problem
If you have continual high ammonia in your aquarium, this is for one simple reason. Your aquarium filtration is inadequate for the amount of food and animals you have been adding to the aquarium. Chronic high ammonia is especially common in turtle tanks because they are very messy animals. If you have chronic high ammonia, you need to reduce the amount of food and animals in the aquarium or increase the amount of filtration on the aquarium. Make sure you are feeding a reasonable amount of food. Most fish only need to be fed once per day, and they should be eating all of the food you add. If uneaten food is accumulating at the bottom of the aquarium, then you are feeding too much. If you have already cut the amount of food as much as you can, then you should consider buying a larger filter. For aquariums with lots of messy animals, especially turtles, it is common to get a much larger filter than the manufacturer ratings suggest. A 50-gallon predator tank or turtle tank may be best with a filter rated for 150-200 gallons. Once you get a properly sized filter on the aquarium, the ammonia issues will go away.