Learn how to decrease ammonia within the aquarium

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If you're just starting a new aquarium, you may have heard about the aquarium cycle and allowed ammonia and nitrite to reach 0ppm each before adding fish. It might seem a bit confusing at first, but ammonia is an important biological aspect of aquatic systems that needs to be dealt with in one way or another. Fortunately, this is mostly done by microorganisms, but sometimes minor intervention such as a water change or chemical conditioner is required.

Read on to find out what ammonia is, how ammonia affects your tank, and what to do to prevent your freshwater or saltwater fish tank from having an ammonia problem!

What is ammonia?

Ammonia (NH3) is a chemical compound that is often due to the deterioration of organic matter and general fish waste in the aquarium. At high concentrations, ammonia poisoning can occur quickly and affect all organisms in your aquarium. For this reason, it is important to fully drive a new aquarium and set up a biological filter.

Ammonia is the first step in easing the nitrogen cycle in an aquarium.

Nitrogen cycle in the aquarium

In short, ammonia is converted to nitrite, which is then converted to nitrate by beneficial colonies of bacteria that populate the aquarium. First, a source of ammonia is needed to speed up the cycle, which is normally created by fish waste. Various aquarium-specific products can be used to dose ammonia, or pure ammonia can be added in another way. Another popular method is the “ghost feed,” in which uneaten food essentially breaks down and releases ammonia.

Nitrifying bacteria then carry out nitrification, which converts this ammonia into nitrites (NO2). These nitrites are then converted into nitrates (NO3) by another type of nitrifying bacteria. At this point, the nitrates can be more easily absorbed by plants and other organisms. As soon as only nitrates are detected with a test kit, the aquarium should be subjected to a major water change. Fish can then finally be added.

Overall, the conversion of ammonia to nitrates takes 3-6 weeks, depending on the circumstances.

What does ammonia do in the aquarium?

While ammonia immediately appears bad in the aquarium, it is food for many microorganisms and plants.

Once the aquarium has been operated, ammonia enters the system via fish waste. Due to certain metabolic functions, fish excrete waste as ammonia, which the good bacteria in your aquarium must convert. All uneaten fish feed and other organic substances that circulate in the tank must also be absorbed by one or the other organism and reintegrated into the feed and nitrogen cycle.

In turn, this bacterium feeds on this ammonia, reducing the level of ammonia in your tank and preventing fish from getting ammonia poisoning. In addition, aquarium plants can easily absorb ammonia, nitrite, and nitrate to grow, which helps lower and maintain these levels throughout the tank.

What causes ammonia in the aquarium?

Now that we know what ammonia is, how does it get into our aquarium systems? There's usually a definite cause for the ammonia levels in our tanks, but sometimes the cause can be the spring water, which we'll get into later.

However, the main causes of an ammonia problem are organic death, overfeeding, overcrowding, or poor aquarium maintenance.


Die-off is one of the biggest factors affecting ammonia levels in your aquarium. Organics begin to break down and rot, which can lead to an overload of nutrients that flood the water column, including ammonia.

A dead fish already affects the water quality after a few hours. It is important to count all of your tropical fish and invertebrates daily to make sure a dead fish does not decay in areas that are difficult to access. All invertebrates should also be considered. Chances are, with an efficient cleaning crew, you won't even have time to find the dead fish or invertebrate as the remains have already been eaten elsewhere. However, it's still best to remove dead cattle when you see them.

Plants can begin to decompose, which can also increase ammonia levels in the tank. While some members of the cleaning crew may be able to handle small plant deaths, it is usually best to prune the plant before it starts to rot and produce ammonia.

If you transfer live filter media or other decorations from another aquarium it is likely that you will experience a death. So some saltwater fish hobbyists start their cycle with living rock. Due to changes in water quality and possible exposure to air for too long, organic matter will begin to die off during transfer. This usually leads to a verifiable increase in ammonia in the aquarium over the next few days.


Overfeeding can be just as dangerous as having a dead fish in the tank. In a more direct way, uneaten food is broken down and nutrients are released into the water column. Uneaten food can also rot if left in the aquarium for too long and produces ammonia.

Believe it or not, many fish actually don't need to be fed that often. While most hobbyists are likely to give their fish 2-3 feeds a day, it is not strictly necessary, especially if the feed is high in protein. More importantly, it is better to give a wider variety of high quality foods in smaller servings than to feed them more frequently on foods that have little to no nutritional value.

Typically, only feed as much fish as they can eat in a few minutes and remove the excess. It is very likely that uneaten food will get stuck in filter pads, which can easily lead to ammonia getting into the aquarium.


Similar to overfeeding, overcrowding not only increases the amount of uneaten food that gets into the system, it also increases direct waste as there is so much more fish. Too many fish lead directly to too much ammonia in the water, which can quickly lead to conditions that are toxic to fish and invertebrates. Worse, when these fish die, they can form an ammonia spike due to the breakdown of organic matter.

For freshwater fish, it is recommended that you only have one inch of fish per gallon of water. More than this can and will result in too much waste and a lack of dissolved oxygen, since more fish means less oxygen and more carbon dioxide.

Bad maintenance of the aquarium

After all, high levels of ammonia in the aquarium can be the result of poor maintenance. In general, it is recommended to do a partial water change in a typical aquarium every week or every other week to keep nutrients down. Vacuuming the substrate also helps remove stuck organics and prevents anoxic areas from building up in the gravel or sand, which can potentially cause nutrients to leak out later.

As we'll discuss later, simply changing the water is the best way to lower ammonia levels in the aquarium. However, it is best to keep an eye on the problem through regular tank maintenance rather than waiting for the problem to show up!

What are signs of ammonia in the aquarium?

The ammonia level can get high very quickly and affect the aquarium livestock. It is important to regularly check all tank parameters and immediately confirm they are where they should be if you suspect there is a problem. But what signs to look out for and how do you know the problem is ammonia levels?


Aquariums have a special smell, but so do ammonia. One of the quickest ways to tell if there is ammonia in your tank is to smell it quickly.

Unless you know what ammonia smells like, it is often compared to the smell of cat urine. The smell is crispy and smelly, similar to vinegar, but even more fragrant. This odor increases with the level of ammonia present, but in general ammonia is detectable by odor in relatively small amounts.

Of course, a test kit is a much more accurate way to determine if ammonia is present, but a little cold can sometimes give an instant yes / no answer.

Fish behavior

In addition to the smell, the behavior of the fish will be the tell-tale sign that ammonia is beginning to affect the livestock. Ammonia poisoning can occur relatively quickly and result in the slow and painful death of fish, invertebrates, corals, and even plants. The main signs to look out for are lethargy, gasping for breath, and redness around the gills.


High levels of ammonia can directly burn the inner and outer areas of your fish. The gills are usually the most affected and may begin to overcompensate with mucus to help ease the burn. This ultimately results in a decreased ability to absorb oxygen, in addition to the fact that the bloodstream is already being affected by the burns. As a result, your fish will most likely lose its appetite. Swimming around can be painful and exhausting, leaving your fish motionless on the bottom of your tank.

Gasp for air

Along with lethargy, you may find that your fish is having difficulty breathing. This is due to the mucus that was created to relieve burns, as well as damage the gills and internal organs. With a tank with high ammonia levels, it is common for fish to breathe heavily and gasp for air. You will usually alternate between resting on the substrate and breathing heavily and panting for air towards the top of the aquarium, since that is where the concentration of dissolved oxygen is highest.

Redness around gills

Your fish may not show any of the above symptoms, but instead develop redness around the gills. This is due to the damage in and around the gills. These red spots can also appear all over the body if the ammonia continues to burn. Not only are these wounds excruciatingly painful, but they can also become infected and create an even bigger problem.

What are the best ammonia removers for aquariums?

It should be noted that when starting a new tank you do not want to lower ammonia unless the values ​​become no longer manageable. For the most part, hobbyists like to keep their ammonia between 1.0 and 2.0 ppm at the start of the cycle. At even higher ammonia levels it is possible to stop the cycle; This means your beneficial bacteria cannot keep up with the amount of ammonia that is being produced in the tank. At this point it may be necessary to manually reduce or remove the ammonia.

There are a few ways to lower ammonia levels in the aquarium, which are all pretty simple.

Water changes

One of the easiest and most efficient ways to lower ammonia levels is to do one or more water changes. Changing the water immediately removes the ammonia from the aquarium and introduces clean water, which helps to dilute the remaining traces of ammonia in the system. It is important for the water in space to change over a few days to ensure that fish or invertebrates are not stressed more than they already are.

Once you've tested your water quality and determined that ammonia is the problem, it's best to do a large water change of around 50%. Let the system realign and test the parameters the next day. If there is still ammonia present, perform another partial water change of approx. 20-30%. Wait another day and test the water again. If necessary, perform partial water changes when the ammonia level is 0 ppm.

Meanwhile, be sure to look for the cause of the high ammonia peak, as ammonia will continue to be added to the water if something in the tank has died or if the aquarium is overfilled.

Chemical supplement

Water changes are usually the easiest way to resolve high ammonia levels. However, sometimes chemical supplements are required which can be helpful in speeding up a new tank.

Beneficial bacteria

There are many beneficial bacterial products that can be introduced into your aquarium to help keep the nutrients in ideal ranges. However, these products do not immediately lower ammonia levels. Instead, good bacteria are added to the aquarium to support the nitrogen cycle more quickly.

hair conditioner

One of the best products to have on hand at any given time is a water purifier that removes chlorine and detoxifies ammonia, nitrite, and other heavy metals. While this won't solve the direct ammonia problem, fish and other animals should be less affected and more time will be given to figure out the source of the problem.

Filter media

The final choice for reducing ammonia levels in your aquarium should be filter media. In an emergency, it is very unlikely that ammonia-specific filter media will be lying around and ready for use.

Filter pads and other media are often used as additional prevention for fish with large bio loads such as goldfish. In general, they do best to create extra space for beneficial bacteria to grow, which makes the nitrogen cycle more efficient. However, once these filter pads and media are used up, they can trap a lot of waste and actually add to the ammonia levels in the aquarium.

How long does it take to lower the ammonia level in the aquarium?

The problem with ammonia in your tank is that you need to remove it as quickly as possible without adding any further stress to your fish. How quickly ammonia leaves your tank depends primarily on the source of the problem. The reduction in ammonia levels to "safer" levels can, however, take place within a few days.

As mentioned earlier, this is normal when ammonia is present in a bicycle fish tank. The ammonia will most likely show up in test kits for at least 1-3 weeks. After that, nitrites and nitrates should appear.

However, if this was a seemingly random spike of ammonia, the length of time will depend on how high the ammonia was allowed to go. Low levels can be resolved with a simple water change, while higher levels may require multiple water changes and chemical supplements.

As always, the underlying problem must be discovered in order to fully resolve the problem.

How do you prevent ammonia in your aquarium?

It is known that an aquarium takes about 1-2 years to mature. During the first year, the tank is most susceptible to algae and bacterial outbreaks, as well as fluctuations in water parameters. Even then, even the most sophisticated tanks can sometimes have high levels of ammonia due to changing conditions in the tank.

If you are one of those people with a young aquarium, then how exactly can you prevent an ammonia spike from occurring?

Test kits

If you don't know what happens to your aquarium chemistry, you don't know what happens biologically. It is important to regularly test the water parameters for at least the first year of a new tank. There are still beneficial bacteria around, new animals are being added, and you will become familiar with how your mini ecosystem works! Some new aquariums even go through mini-cycles because too much cattle were added before the beneficial bacteria could handle the increased bio-load.

It is important that you test your water to get a baseline reading of the water parameters and determine where your tank works best. Remember, while there is an "ideal" set of water parameters for freshwater and saltwater tanks, some aquarium systems are simply better outside of this range. It can take some time to figure out where your aquarium is at its best.

However, when the water parameters are out of this range, it is time to take some precautionary measures. In addition to a current test kit, an emergency plan should always be drawn up.

Test spring water

Ammonia does not only appear alone in an aquarium. This is usually the result of organic death, overfeeding, overfilling, or poor tank maintenance. However, there are times when it looks like ammonia just appears out of nowhere.

This is most likely due to ammonia being fed into the system from an external source. One of these possibilities is the use of spring water with a verifiable ammonia content. Many freshwater enthusiasts like to use tap water so they don't have to remineralize their water later, but public water is subject to different regulations depending on the location. This means that there may be some traces of ammonia from your tap in the water.

At the same time, ammonia could potentially just as easily be found in any other water source such as distilled or reverse osmosis water (RO). Whether this is due to dirty water filters or corroded pipes, unknown levels of ammonia can enter the aquarium without even realizing you are adding it.

While you can have confidence in your water utility most of the time, it may be a good idea to test the parameters from time to time to get a baseline. Tap water can also be sent for ICP (inductively coupled plasma) analysis, or a full analysis can be requested from the local water company.

Living plants

Live plants are not a good option for getting rid of ammonia in an aquarium. Rather, living plants can be used well to create a healthy, self-sustaining ecosystem that balances its own inputs and outputs.

Aquarium plants generally prefer nitrate (NO3) as the main essential nutrient, but they can also absorb ammonia (NH3), ammonium (NH4) and nitrite (NO2). This means that a link is made between the amount of waste in the tank and the health and growth of the plants in the system.

Living plants have many advantages, such as: B. Providing shade and shelter for a range of fish and invertebrates and creating a natural backdrop. If you have a higher bio load, or just want to make sure your fish thrive as well as possible, live plants will help absorb some of that extra ammonia.


Ammonia is an essential part of a healthy and thriving aquarium. However, if your system lacks the number of good bacteria it needs to keep up with ammonia influx, a problem will arise in the aquarium. High ammonia levels can be the result of death, overfeeding, overcrowding, and poor aquarium maintenance.

Fortunately, high levels of ammonia are usually corrected with multiple water changes. However, chemical supplements may be required in emergency situations. Otherwise, high ammonia levels can be prevented by regularly doing an ammonia test, checking the parameters of the spring water being used, and / or using live plants to naturally lower ammonia and ammonium.

If you have any questions about the nitrogen cycle, how to remove ammonia, or if you have any experience with a serious ammonia problem in your aquarium, don't hesitate to leave a comment below!

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