Ammonia present in tank? Read here


It seems like we’ve been getting the same question over and over again: “Why is there ammonia in my tank?”. Before you go and make a thread about it, ask yourself these questions:

1) Did you cycle your tank?

If you did not, the ammonia that you are seeing is the beginning of aquarium nitrogen cycle. During the nitrogen cycle, you will first see a rise in ammonia, then the ammonia is converted into nitrites, and finally the nitrites are converted into nitrates, thus completing your cycle. The nitrogen cycle is essential to keeping fish. Without it, you'll experience tons of problems along the way.

For further information the nitrogen cycle:
Aquarium Nitrogen Cycle (Page 1)

4 Methods to Fishless Cycling
4 Methods to Fish-in Cycling

2) Have you added fish recently?

The addition of too many fish can cause the bioload of the tank to go up way too quickly, not allowing the filter to catch up. With the bioload of the tank up, the amount of ammonia being produced will be too much for beneficial bacteria to process, thus causing an ammonia spike. To prevent this from occurring, add only 2 - 3 fish to an aquarium at a time, then wait 10 - 14 days until the next addition of 2 - 3 fish, and so on. Doing this will allow the filter to keep up with the bioload of the tank.

3) How much do you feed? How often?

Overfeeding the tank can cause excess fish food to be left on the bottom of the aquarium. This fish food will then decay and produce ammonia. To prevent this, feed as much as the fish can handle (basically enough that everyone gets their fill but nothing is left over). It may take you a few tries to find how much to feed. Also, I would generally recommend to only feed once a day, or once every other day. Fish can go long periods of time without food, feeding more than once a day is more than enough for your fish.

4) How often do you do maintenance?

Water changes are important to keeping your water parameters in check. Just because you have a filter doesn't mean you can slack on or not do water changes. A filter alone can keep extend water quality and slow down chemical buildup, but it cannot stop the decline of your water quality. The point of a water change is to replace old water with nutrient filled new water. The lack of water changes will allow the build up of ammonia in the aquarium. Generally you should do weekly water changes <25% - 50%> with an additional gravel vacuum. Gravel vacs allow you to suck up any extra fish food, poop, or other debris around the aquarium that may produce ammonia.

5) Have any fish or plants died recently?

It may not seem like it, but one small fish/plant that dies can bring quite the amount of ammonia to ones aquarium. Always make sure to do a head count everyday. You never know if a fish is stuck somewhere dead if you don't. If you are to see any dead/decaying fish or plant, remove immediately.

6) Have you recently replaced a filter cartridge?

As you cycle your, bacteria collects on your filter (also known as beneficial bacteria). This bacteria helps convert ammonia convert to nitrite and nitrite into nitrates, helping to keep your tank stable. When you remove the filter cartridge (that contains all the beneficial bacteria) and replace it with a new cartridge (that has no bacteria on it whatsoever), your tank's cycle will relapse (also known as a 'minI cycle'). This minI cycle is like cycling your tank all over again, ammonia and nitrite will start to rise. It's just a big mess. If your filter cartridge is looking a little dirty do not replace it. Instead lightly swish it around in a container of old tank water that you've collected during a water change.

7) Is your filter adequate for your tank?

An inadequate filter can cause a build up of ammonia in an aquarium. When looking for a filter, you should look for the GPH (Gallons Per Hour), not the aquarium rating. You should get a filter that provides a GPH 10x the volume of the tank. i.e a 20G tank needs a filter with 200 GPH (10 x 20 = 200). If tank is stocked and your filter is lacking, you will begin to see a rise in ammonia. Over stocked tanks go alongside with filters. If you are to have an over stocked tank and your filtration lacking, your are likely to see ammonia in the tank.

9) Have you used any type of medication or chemical to alter your water parameters?

One thing I strongly urge against is using chemicals to alter your water parameters or medication that others haven't advised to use. These things can do more harm than good for your fish. I've had an "ammonia remover" raise the ammonia in my tank rather than remove it.

10) Have you tested your tap water for ammonia?

If none of the above have applied to you, then check the source of water you use for water changes. To ensure the safety of their customers, water companies have used chloramine to treat their water. Chloramine is just chlorine bound to ammonium. By adding the tap water to your aquarium, you are essentially adding ammonium. To prevent ammonia being released in the aquarium, make sure to buy a water conditioner that treats for chlorine and ammonia.

11) What kind of test kit are you using?

I cannot stress enough how important it is to have a liquid test kit. Sadly if you are using test strips to test you water, they are giving you false readings. I highly recommend getting the API Master Liquid Test kit for accurate results.


In order to get your ammonia down to a safe enough lever for your fish (<.25 ppm or less), I'd recommend doing daily partial water changes <15% - 20%>. Do not test immediately after your water change, wait a few hours (the water conditioner may affect the results of the test). I would also recommend a water conditioner such as Prime. It detoxifies ammonia and nitrite for a total of 24 hours. It's great in situations where you are needing to do back to back daily water changes. The number of times you will have to do this will depend on the situation.


As well as my own knowledge on the subject.

I don't feel as if this is the best write up and that it could so please feel free to comment and add suggestions. If you are wanting something changed or removed, please feel free to contact me!

Thank you


Love it! Really informative!


Thank you very much!

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