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How To Lower Ammonia Levels In Fish Tank Naturally

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By Lindsey Stanton

fish tank filter pipe and little fish

Ammonia is a huge problem in planted tanks and normal fish tanks. In fact, it is highly poisonous to any and all living organisms in your fish tank.

It will quickly poison, eat away at, and eventually kill all of the plant and fish life in your aquarium. So, we are here today to help you figure out how to lower ammonia levels in your fish tank.

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What Is Ammonia?

Ammonia is a colorless gas that has a very distinct odor and is composed of both nitrogen atoms and hydrogen atoms. It has the chemical symbol NH3. It is a naturally occurring substance that is produced by the human body, as well as in nature. It can occur in water, soil, air, and more.

Ammonia makes for a great cleaner, which is why it is used for many industrial cleaning applications, but it is also poisonous, especially if the ammonia level in your fish tank hits a certain amount.

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What Causes Ammonia in Fish Tanks?

aquarium nitorgen cycle

There are several reasons why your fish tank might have high ammonia levels. If your aquarium has high ammonia levels, any of the following reasons may be to blame.

1. Uneaten Fish Food in the Aquarium

goldfish eating flakes
Image Credit: Leonardo Macedo, Shutterstock

One of the biggest reasons why the ammonia level in your aquarium might be high is because of uneaten food. If uneaten food remains in the tank for too long, it will begin to rot and decompose.

As the uneaten food rots and decomposes, it creates and releases ammonia into the water. Therefore, if you have an ammonia problem, feeding your fish less, cleaning the tank, and doing a water change to remove uneaten food can help.

2. Decaying Plants

Credit: Enadan, Shutterstock

Plants can also be a cause of a high ammonia level in a fish tank. If your plants are not doing well, they may start to rot or decompose in the tank.

If you have rotting plants in your tank, like with uneaten fish food, they will begin to create and release ammonia into the aquarium, which can then lead to excessive ammonia nitrite levels.

To solve this issue, a water change can help, but removing decaying plant matter is the number one option. If you take good care of your plants and have them in the proper water parameters, this really shouldn’t be a problem.

3. Excessive Fish Waste

Image Credit: kaori, Pixabay

If you have a fully stocked fish tank, especially if you feed them too much, they will create a lot of waste. Fish waste is a leading cause of excess ammonia levels in the fish tank.

Once again, cleaning the tank and performing a water change can help, but feeding your fish less and ensuring that you have a working filter will help reduce ammonia levels in the tank the most if this is the cause.


4. Improper Tank Filtration

goldfish in dirty unclean tank
Image Credit: Chaikom, Shutterstock

Your aquarium filter is the best tool at your disposal to get rid of ammonia in the tank. Your filter is a big part of the aquarium nitrogen cycle, particularly the biological filtration aspect. Beneficial bacteria that grow in the filter break down ammonia in the tank by turning it into nitrite and nitrate.

If your filter is not up to handling the water volume in the tank, you have several fish, the filter is broken, the biological media is old, or you don’t properly clean and maintain your filter, it can quickly lead to this problem.

Excessive levels of ammonia can almost always be attributed to a lack of proper filtration in the tank. To get rid of ammonia, you can clean your filter, replace the biological media, and ensure that the filter is designed for your tank.

5. A New Tank – The Nitrogen Cycle in an Aquarium

acrylic aquarium
Image Credit: BLUR LIFE 1975, Shutterstock

If you have a new tank with new fish, the number of beneficial bacteria in the tank will be lower than it should be. It takes between 3 to 6 weeks for the little organisms to multiply to the point where they can get rid of excessive levels of ammonia.

A new tank is always going to have excess levels of ammonia until the nitrogen cycle has been completed a couple of times. Therefore, to remove ammonia from the fish tank, waiting for a while for the cycle to get going is essential, and adding new fish to the aquarium before this is definitely not recommended.


6. Your Tap Water

Image Credit: Ammit Jack, Shutterstock

Yes, your tap water may also have ammonia in it, and before you use water from the tap, make sure to let it sit for 24 hours.

Also, make sure to use a water conditioner and ammonia remover before adding the water to the tank.

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How Does Ammonia Affect Fish?

Simply put, NH3 is highly toxic to fish. It causes chemical burns on the skin and on the gills, and as it absorbs into the body of the fish. It burns them from the inside out.

It will burn interior tissue and organs and end up causing mass organ failure and eventually death.

What Should Ammonia Levels Be In My Fish Tank?

checking water quality
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The level of ammonia in your fish tank should be as low as possible. Fish are very sensitive, and even small amounts can cause a problem.

Always make sure to test the water to ensure that the levels are acceptable. 0 ppm is best, and remember that anything over 1 ppm (part per million) can be harmful to fish.

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How To Lower Ammonia Levels In Fish Tank: 7 Ways

Now that we have covered what is ammonia in a fish tank, let’s now look at 7 ways of reducing ammonia levels;

1. Changing The Water

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One of the easiest, fastest, and most effective ways of decreasing ammonia levels in the water of your fish tank is to simply replace the old and contaminated water with fresh water.

To be fair, regular partial water changes are something that you should be doing on a weekly basis anyway. If you see that there is too much ammonia in the water, you can always perform the partial water changes more often.

If you aren’t changing the water enough, the substrate (we have reviewed some good substrates in this article), when stirred up, causes cloudiness in the water. Simply remove about 30 percent of the water with a scoop or small bucket while being careful not to agitate the fish or plant life.

Put the same amount of fresh water in a bucket with some dechlorinating agents, let it sit for a few hours, make sure the temperature is roughly the same as the current tank water, and slowly pour it back in.

In terms of numbers, this process should drop ammonia levels by 30%, or even more if you change more water. Keep in mind that it is not recommended that you ever change more than 30% of the water at once, or you are putting the health of your fish at serious risk.

2. Remove Waste & Unwanted Organic Matte

gravel cleaner

Since rotting food, fish waste, and old plants can all cause ammonia, another easy solution to your ammonia problem is to remove the things creating or releasing it.

Of course, you aren’t going to remove the fish from the tank because they are the whole point of having an aquarium, but there are several other things that you can do.

Use a scoop or gravel filter (this one is good) to clean the substrate of any and all waste, uneaten food, and decaying plant matter. This will go a long way in lowering ammonia levels. Also, you can clean out the filter in your tank to make it more efficient at its job.

3. Less Feeding

Image Credit: Alexander Geiger, Shutterstock

If your fish leaves behind a lot of uneaten food, or if you realize that your fish produce an excessive quantity of waste when they shouldn’t, it might be time to start feeding your fish less.

Since both uneaten food and fish waste release ammonia, feeding them no more than the required amount may help to reduce ammonia levels.

4. Healthy Bacteria

Gold fish aquarium
Image Credit: Janelle Lugge, Shutterstock

Another method that you can try in order to lower the ammonia levels in your fish tank is to introduce some healthy and beneficial bacteria into the equation.

You can try adding some new fish into the water, adding gravel from an old tank, or using a filter with biological filtering. The bacteria will then break down the ammonia into nitrites and eventually into nitrates. Both nitrites and nitrates are still harmful to your fish, but not nearly as much as ammonia.

5. Lowering The pH Level

Aquarium Pharmaceuticals 30B pH Down

When your water is basic or over 7.0 on the pH scale, ammonia tends to be present in higher concentrations because it does not break down as well as basic water. You can go to your local pet store and buy chemical pH adjusters to lower the pH levels in your fish tank.

Just remember that your fish have a specific pH range that they need to live. Lowering the pH levels in your fish tank will not actually remove the ammonia from the water, but it will make it less potent and dangerous to your fish.

You can also try adding new gravel into the tank as opposed to coral or sand. Coral and sand release calcium into the water, which will cause a rise in pH levels.

6. More Aeration

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Having a lack of aeration in the water is harmful not only for your fish as they try to breathe but also because it allows ammonia to stay in the water longer.

On the other hand, increasing the aeration will increase the rate at which the ammonia diffuses into the air above the water, thus decreasing its levels in the fish tank. The only way to really do this is by buying an air pump.

If you don’t have a pump, we have some other tips here.

7. Neutralizing Drops

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Credit: Skumer, Shutterstock

The final method is to use neutralizing drops. They will not actually remove the ammonia from the water, but they will render its toxic effects non-existent.

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Signs Of High Ammonia Levels In Fish Tank

There are a few signs to look out for, such as;

  • Appetite loss
  • Gills inflamed (pink around gills)
  • Eyes inflamed
  • Labored breathing
  • Fish surfacing to the top more than normal

If you are in doubt about the ammonia levels, you can either use test strips or a liquid test kit (we think liquid ones are better personally) to check the water.

What Is The Best Ammonia Remover For Aquariums?

API AMMO-LOCK Ammonia detoxifier

API AMMO-LOCK Ammonia detoxifier

This is one of the most highly-rated ammonia removers out there, and it’s said to reduce ammonia in tap water and your tank water.

It can be used in saltwater and freshwater tanks. All you have to do is pour it into the aquarium according to the instructions and repeat the process every 2 days until there is no ammonia in the tank. It’s fast, simple, and very effective.

  • Very effective.
  • Easy to use.
  • A little goes a long way.
  • Clear instructions.
  • Excessive use is not healthy for fish.

Check pricing at Amazon

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Commonly Asked Questions

How To Lower Ammonia Levels In Fish Tank Naturally

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There are indeed various ways to naturally lower the levels of ammonia in a fish tank. Here is a quick overview of the most effective methods.

  • Do a partial water change of roughly 30%. This should automatically remove 30% of the ammonia content in the water. However, be careful not to change more than 30% of the water per week since it can cause more problems.
  • Scoop out any organic matter that should not be in the aquarium. This includes rotting plant matter, old food, fish waste, and dead fish as well.
  • Reduce the amount and frequency of food you give your fish. The less food they get, the less waste they produce.
  • Introduce higher quantities of beneficial bacteria into the water, which work to break ammonia down rapidly.
  • Slightly increase the aeration and oxygenation levels in the tank water.

How Do You Treat Ammonia Poisoning In Fish?

Unfortunately, there is absolutely no cure for ammonia poisoning in fish, which makes prevention all that much more important.

How Long Does It Take For Ammonia To Build Up In A Fish Tank?

goldfish in aquarium
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Generally speaking, it takes anywhere from 30 to 45 days for ammonia to build up in a fish tank to levels that can harm and kill fish.

Of course, this will depend on several factors, including the number of fish in the tank, the frequency and amount of feeding, if you have a good filtration system, how much oxygen is in the water, and how many beneficial bacteria you have.

If conditions are not ideal in the least, it may take as little as 2 weeks for ammonia to build to levels that can be toxic to fish.

How Long Does It Take For Ammonia To Go Down?

If you are experiencing an ammonia spike in your aquarium, it will take up to 6 weeks for it to go back down. However, it depends on the quality of the nitrogen cycle in your tank.

If you have plenty of beneficial bacteria in your tank that are breaking the ammonia down, it may take only 2 to 4 weeks, but if you don’t have beneficial bacteria, it will take much longer, or it might not go down at all.

This process can be quickened by adding more beneficial bacteria to the water and by doing regular partial water changes.

How Long Does It Take For Fish Food To Turn Into Ammonia?

Goldfish eating food
Image credit: Kaikoro, Shutterstock

Between the process of decomposition and the bacteria breaking food down, it will take about 2 to 4 days for uneaten fish food to turn into ammonia.

Is .25 Ammonia Harmful To Fish?

Technically speaking, any amount of aquarium ammonia can be harmful to fish. You should do everything in your power to prevent ammonia from building up in the aquarium.

Ammonia levels of 0 parts per million are best. 1 part per million of ammonia in the water is still acceptable, although definitely not ideal. Anything over 2 parts per million has very real potential to harm your fish.

So, realistically, 0.25 ppm is not severe, and it should not harm your fish, but it is still worse than no ammonia at all.

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Ammonia, even in the smallest of quantities, can end up making your fish sick and killing them very quickly, and it’s important to know how to identify and get rid of ammonia, which hopefully we have helped you accomplish. Try to test your water for ammonia on a regular basis, and if there is too much of it, use any of our methods to rectify the situation.

See also: 6 Helpful DIY Fish Tank Lids (With Pictures)

Featured Image Credit: mariait, Shutterstock

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