Aquarium Ammonia 101: Causes, Solutions, Products & More

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Even after years of experience, I admit that ammonia spikes can be a serious headache. That is especially true for aquarists who deal with the issue for the first time, as ammonia can be pretty difficult to eliminate.

So, after years of learning from mistakes, I decided to gather some of the most frequent questions into one complete guide. In most cases, I will link to another article that I wrote so that you get the picture more thoroughly. 

Ultimately, in the last part of this article, I will list some essential tips to help you get rid of the ammonia in your tank. I will also include my personal gear collection that I found most helpful in dealing with ammonia spikes.

So, without further ado, let’s dive into it.

Aquarium gravel cleaner that removes uneaten food and fish waste.

How Does A Fish Tank Get Ammonia?

Fish tanks typically get ammonia via organic matter decomposition, including dead fish and food residues. Some other sources include dead plants and fish waste, especially from species like Oscars, Plecos, Clown Loaches, and Goldfish.

Ammonia is a byproduct of protein metabolism. In a healthy aquarium, nitrifying bacteria will turn it into nitrite, which will later turn into nitrate.

Fish also secrets ammonia from their gills. That is the primary source of ammonia that isn’t related to the decomposition of organic matter. For that reason, overcrowded tanks suffer from ammonia spikes pretty frequently.

Still curious? Click here for more information on how fish tanks get ammonia. In there, I also discussed how tap water can be a source of ammonia and which product can help you with that.

Do I Need To Add Ammonia To My Fish Tank?

You need to add ammonia to your tank when it’s being cycled. By reaching 2-4 ppm levels, fish owners stimulate the formation of nitrifying bacteria, which are essential to the nitrogen cycle.

Ammonia is bad for your fish, and there is no doubt about it. But when you’re cycling your tank, there aren’t any fish. That is in contrast to nitrifying bacteria that are starting to form quickly.

And unlike fish, nitrifying bacteria won’t suffer from ammonia. In fact, it’s quite the opposite; they will feed on it and flourish.

You can add ammonia to a brand new tank by introducing objects from cycled tanks. A common practice would be placing the substrate. 

As time passes, you will see the ammonia slowly decreasing. When it reaches 0 ppm, the tank is cycled. You can add more ammonia just to be sure. Either way, don’t add your fish before the ammonia is zero.

Some use commercial ammonia solutions to feed their nitrifying bacteria.

Caught your attention? Click here for more information on whether you need to add ammonia to your fish tank. You’ll also find a few products I recommend that can speed up this process.

How Long Does It Take For Ammonia To Turn Into Nitrite?

It usually takes 7 to 10 days for ammonia to turn into nitrite, and after another 14 to 21 days, nitrties will start turning into nitrates. The entire process, known as the nitrogen cycle, takes between 6 and 7 weeks.

Nitrifying bacteria will naturally build in a brand new tank. However, these bacteria take at least a week to mature to a level they can turn ammonia into nitrite.

If you measure the water parameters with a test kit, you’ll notice that the ammonia gradually declines while nitrite starts to build up. After two more weeks, the bacteria will start producing nitrates.

Wish to learn more? Click here for more information on how long it takes for ammonia to turn into nitrite. I made sure to include some practical ways to speed up the nitrogen cycle process.

How To Check Ammonia Levels In A Fish Tank Without A Kit?

You can roughly conclude that the ammonia levels are higher than 0 ppm if your fish breathe heavily, swim lethargically, and develop red patches resembling bleeding. Sometimes, the water will be cloudy and smell like rotten eggs.

Test kits are necessary when measuring the precise ammonia levels in your tank. But your fish can also tell you something is wrong by how they behave.

However, some signs are not specific to high ammonia concentrations. For example, fish can breathe heavily when they don’t have enough oxygen. Obviously, that can happen when the ammonia is at zero.

A picture of a cloudy tank with an ammonia level of 0.25 ppm.

Sounds interesting? Click here for more information on how to check the ammonia levels without a test kit. I also gave specific instructions on what to do if you notice those signs.

What Are The Signs Of Ammonia In A Fish Tank?

These signs indicate that ammonia has spiked in your tank: 

  • Your fish start to swim erratically. 
  • The fish hide for no apparent reason. 
  • Your fish breathe heavily, gasping for air. 
  • You will notice pinkish or reddish colorations on the fish’s skin.
  • Your fish will lose their appetite. 
  • You will suddenly lose many of fish your fish. 
  • In severe cases, the fish will develop red streaks and patches. 

The signs above suggest an ammonia spike, especially if you see at least two of them simultaneously. Even without a test kit, you’ll know you have an ammonia situation.

If you do have a test kit, that will be the right moment to check the water. Levels of 0.25 ppm or higher require an urgent water change.

This gourami developed pinkish gills (usually 0.25 ppm ammonia and above).
This goldfish developed red patches due to ammonia poisoning (usually 0.5 ppm and above)

Still curious? Click here for more information on the signs of ammonia in fish tanks. In this article, I also discussed whether fish can recover from ammonia poisoning and how quickly it may kill fish.

What Do The Aquarium Ammonia Levels Mean?

This table describes the impact of each ammonia level on aquarium fish:

0.00 ppmSafe
0.25 ppmMildly Toxic
0.50 ppmToxic
1.00 ppmDeadly
2.00 ppmDeadly
4.00 ppmDeadly

As a rule of thumb, the only safe ammonia level is 0 ppm. Anything higher than that can stress and kill your fish.

Some fish can tolerate 0.25 ppm. They will be stressed, but if they have lived at this level for a long time, they might survive.

Levels of 0.50 ppm won’t necessarily kill your fish, but they will be highly stressed. From this level, you can assume that a lot of debris is hidden in your substrate.

Levels of 1.00 ppm or higher are deadly and will kill most fish in no time. These are considered an emergency and require roughly 50 percent water change in addition to a water conditioner.

Caught your attention? Click here for more information on the different ammonia levels and their impact on fish. You will also find an interesting discussion where I explained how low ammonia levels could be more toxic than high ones.

Does A Water Conditioner Remove Ammonia?

A water conditioner doesn’t remove ammonia, but it neutralizes it. By binding to the toxic element, water conditioners detoxify ammonia, leaving it in its non-toxic form. So, the ammonia will remain in your tank, but it won’t harm your fish.

Water conditioners are top-rated because they neutralize ammonia pretty quickly. They are definitely a good solution when the ammonia is 0.25 ppm and higher.

But you shouldn’t rely on these products solely, as they are a temporary solution. In addition to a water conditioner, you should perform a significant water change and eliminate waste and food residues from your tank.

In other words, it is better to prevent the ammonia from spiking in the future rather than fighting it with water conditioners.

Wish to learn more? Click here for my discussion on whether water conditioners remove ammonia. In contrast to a water conditioner, I included some practical ways that actually remove the ammonia from your tank.

How Do I Stop Ammonia From Building Up In My Aquarium?

These steps will help you prevent ammonia from building up in your tank: 

  • Add nitrifying bacteria via a filter from a cycled tank. 
  • Replace 30 percent of the water each week. 
  • Apply a water conditioner in every water change.
  • Siphon the substrate to remove food residues and waste. 
  • Try not to clean the filter too thoroughly. 
  • Feed your fish the amount they can consume within two minutes. 
  • Introduce floating plants to your tank.

When it comes to ammonia, it is better to prevent it from building up rather than fighting spikes. If you don’t eliminate the source, you will find yourself in an endless battle.

Conducting a significant water change after an ammonia spike.

Sounds interesting? Click here for more information on how to stop ammonia from building up in your tank. In there, you will find detailed instructions on each step.

What Are The Most Common Reasons For Ammonia Spikes?

If you have an ammonia spike, these are usually the causes:

  • Your tank has too many fish.
  • There is a lot of fish waste hidden in your tank.
  • There is uneaten food on the substrate.
  • Your tap water contains chloramine.
  • The tank doesn’t have enough nitrifying bacteria.

You should follow this checklist if ammonia has spiked in your tank. Regarding the number of fish, stick to the one inch per gallon rule. If that already applies, possibly one inch per two gallons is better for your particular case.

Then, get an aquarium vacuum and siphon the substrate. That should be done every one to two weeks. It will eliminate waste and uneaten food without stressing your fish.

If your tank is new, you probably don’t have enough nitrifying bacteria yet. In this case, you can get the Fritz Aquatics Nitrifying Bacteria (link to Amazon).

Still curious? Click here for more information on aquarium ammonia spikes. I also discussed how long ammonia spikes typically last and which ways are best to deal with it. 

How Do I Get Rid Of Ammonia In My Fish Tank?

Ammonia is inevitable. You can’t keep it out of the tank. However, once you detect ammonia, you can use any one of the following methods to eliminate it:

1. Making A Water Change Properly

Water changes are the backbone of a healthy aquarium. You cannot successfully rear fish without this practice. A water change is precisely what it sounds like.

You take a certain percentage of water out of the aquarium. Then you replace it with an equal volume of newer, cleaner water. The goal is to take some of the pollutants out of the tank.

What about the pollutants that remain? Well, you cannot eliminate all the toxins unless you change 100 percent of the water. However, adding new water will dilute those dangerous remnants, including ammonia and nitrites.[1]

Professional aquarists encourage newcomers to prioritize water changes because they are cheap, easy, and effective.

Admittedly, you have to match the new water’s parameters to the tank’s conditions, which can complicate matters. You don’t want to drastically alter the equilibrium of the aquarium by introducing water with the wrong pH and temperature.

But suppose you take the necessary measures beforehand, such as applying conditioners to the new water. In that case, you can eliminate ammonia by performing a water change without harming your fish in the long run.

Making a water change is crucial, but it goes hand in hand with gravel vacuuming.

The frequency and percentage are crucial. You can change 10 to 15 percent of the water every week. But that will only work for smaller tanks. Those figures rise to 20 percent for larger tanks.[2]

You can afford to change the water twice a week if the changes are small (10-15 percent). But a partial water change is significant. Therefore, you should only change the water once a week or during emergencies.

It isn’t unheard of for people to change as much as 90 percent of the water, especially when ammonia has reached toxic levels.

However, a paper in the National Library of Medicine (Aquarium Microbiome Response to 90 Percent System Water Changes) warns against massive water changes.[3] 

It suggests that water changes as significant as 90 percent can affect the bacterial community structure. Therefore, large water changes are a last resort. Don’t use them unless your fish are in danger. 

2. Managing The Aquarium Filter

Ammonia normally enters the tank via leftovers, fish waste, dead organisms, and other forms of rotting organic matter.

Fish will excrete ammonia through the gills. But the quantities are not large enough to produce a sudden ammonia spike, not unless you have crowded conditions. 

Leftovers and fish waste are the biggest culprits. You cannot rely on water changes to remove them. Water changes must work hand in hand with filters. 

Filters serve some fundamental purposes:

  • Debris

They will capture and remove debris from the water. Like water changes, filters cannot perform this task alone. Some forms of debris require manual removal. However, a filter can capture significant quantities of pollutants.

  • Bacteria

If you cycled your tank, you already know that aquariums have beneficial bacteria that turn ammonia into nitrites and nitrates. Filters provide a platform for nitrifying bacteria to grow.

This is why ammonia increases when you change the filter media. Removing the filter media reduces the population of beneficial bacteria significantly. 

  • Oxygen

Nitrifying bacteria are obligate aerobes.[4] They use oxygen to process nitrogen. Admittedly, they can survive under low oxygen conditions. Nonetheless, it helps to have a filter.

The device will agitate the water, increasing the gaseous exchange at the surface and preventing oxygen deficiencies in the long run.

Cloudy aquarium water indicates you should test for ammonia.

If you still have ammonia despite the presence of a filter, you should take the following precautions:

  • New Filter

If your old filter is too weak, get a new one. Your selection of a filter should account for the tank size and number of fish. 

The filter can’t be too powerful. Strong currents will cause distress in fish, exhausting the creatures and complicating the feeding process.

On the other hand, you don’t want a weak filter. The device should turn over the water four times per hour. Otherwise, you can’t trust the hardware to keep the tank clean. 

  • Filter Media

Don’t replace the entire filter media. You should also avoid tap water when washing the filter. The chlorine will kill the nitrifying bacteria. 

If you have already killed the nitrifying bacteria, get filter media from an established tank. It will replace the colonies you lost.

The circled part is the aquarium media, containing essential bacteria that shouldn’t be removed.
  • Maintenance

Don’t forget to clean the filter. The device is supposed to trap pollutants like fish waste and leftovers. Those pollutants will rot to produce more ammonia unless you remember to unclog the filter.

I personally recommend using the water in the tank to clean the filter. That is pretty standard practice, as it is the best way to protect the nitrifying bacteria.

  • Ammonia Removers

Some filters are specifically designed to remove ammonia. They have resin products that capture and eliminate the substance. They also offer a larger surface area for beneficial bacteria to grow.[5]

Smaller aquariums can make do with ammonia chips. However, larger tanks will benefit from filters with ammonia removal systems. They provide a long-term solution to the ammonia issue.

One prominent product in this category is the Hygger Aquarium Double Sponge Filter (link to Amazon). This filter contains media sponge balls featuring a large surface area. They are specially designed for the purpose of nitrifying bacteria growth.

3. Vacuuming The Substrate

Do you vacuum the substrate? Filters and water changes are not enough. You have to remove some pollutants manually. That includes fishing dead organisms out of the water with a net.

But what about the leftovers and fish waste? They typically sink to the bottom. And if you have gravel, you won’t have the option of manually removing the pollutants.

You have to vacuum the substrate. Otherwise, the waste and leftovers will increase the ammonia concentration once they decompose. 

4. Lowering The Water pH

Many aquarists do not understand the connection between pH and ammonia. They don’t realize that a lower pH makes ammonia less toxic. This gives you more time to perform water changes.

Reverse osmosis is popular among aquarists that want to lower the pH. It will also remove dangerous substances such as chlorine and phosphates. 

Because it uses a de-ionizer, you can trust reverse osmosis to eliminate silicates and other pollutants of that ilk.[6] But for most aquarists, it might be cheaper to use peat moss driftwood and almond leaves.

It should be reiterated that lowering the pH cannot remove ammonia. It merely gives you the room you need to act. Your fish won’t die as quickly in an ammonia-rich tank with a low pH. If you don’t act, you will lose your fish.

5. Cycling Your Tank

Cycling is the first step you take before you introduce your fish. If you forgot to cycle the tank or added the fish before the cycling process was complete, the ammonia would continuously spike because you don’t have enough nitrifying bacteria.

While cycling a tank with fish is possible, you are better off moving the fish to a separate container before cycling the tank.

To cycle a tank, you must first raise the ammonia concentration. The objective is to attract nitrifying bacteria. The ammonia concentration will remain high until a colony of nitrifying bacteria grows and turns the ammonia into nitrite.

Even though nitrite is less dangerous than ammonia, it is still toxic. The last thing you want is to expose your fish to high levels of ammonia and nitrites. Although, some aquarists use fish to cycle new tanks.

They want the fish to create a mess to increase the ammonia in the water. Ultimately, this is your decision to make. If you have the skill to keep the fish alive in a cycling tank, you don’t have to move them. 

  • If all that sounds overwhelming, here is a video that will show you how to cycle your tank quickly using the Fritz nitrifying bacteria I mentioned earlier:

6. Using Water Conditioners

Some think water conditioners are the easiest answer to ammonia, even better than water changes. After all, you only need a few drops to neutralize the ammonia. 

On the other hand, water changes require a lot of time and effort. However, you have to realize that water conditioners do not remove ammonia. They are similar to the pH.

They give you room to take concrete action by neutralizing the ammonia. You can also trust them to provide immediate relief. However, they are not a permanent solution. Think of them as a band-aid.

What I typically recommend is the Seachem Prime Conditioner (link to Amazon). This product is excellent in detoxifying ammonia and neutralizing chlorine.

7. Introduce Floating Plants

Plants are far more beneficial than people realize. Everyone knows that live plants provide hiding places for fish. They also recognize that plants produce oxygen.

In other words, they can prevent oxygen deficiencies from taking root. However, you may not realize that plants absorb ammonia.

Additionally, they will extract nutrients from waste and leftovers. Don’t expect them to remove all the ammonia. They will simply compliment all the other steps you’ve taken.

When choosing the specific type, I recommend getting a floating plant. These will absorb more ammonia during photosynthesis. 

Here are some common examples:[7]

  • Duckweed (Lemna minor)
  • Hornwort (Ceratophyllum demersum)
  • Amazon Frogbit (Limnobium laevigatum)
  • Dwarf Water Lettuce (Pistia stratiotes)
  • Water Spangles (Salvinia minima)
  • Smooth Frogbit (Limnobium laevigatum)
Floating aquarium plant Limnobium laevigatum

8. Creating Enough Aeration

The toxic component of ammonia is NH3, which is a gas that dissolves in water. Therefore, you can force NH3 out of the water by increasing the aeration. Large tanks require air pumps.

But if you have a conventionally sized aquarium, you can make do with air stones. You cannot rely on filters in this situation. 

Usually, filters work with air stones and pumps to prevent oxygen deficiencies. But if you have high ammonia levels, a filter is insufficient. Although, you should still get one.

If you don’t have an air stone, I would personally recommend the Hygger Aquarium Air Stone (link to Amazon). This one is extremely quiet and pretty affordable.

My Ammonia Removal Equipment Summary