How To Lower Ammonia In Fish Tank (9 Steps Guide)

Ammonia is deadly to your fish.

It is the most common cause of death of a fish in the aquarium.

If you notice a high ammonia level in your aquarium, you must immediately do some measures to lower it.

In this brief article, I will discuss how to lower ammonia in fish tanks, and our ultimate goal is to remove it altogether.

What Is Ammonia?

Ammonia (NH3) is a chemical byproduct that is produced from decomposed wastes of aquariums. At high levels, ammonia poisoning can promptly embed in and affect all the organisms in your aquarium. 

As a result, it is crucial to completely cycle a new fish tank and keep an effective biological filter.

Ammonia is the very first step in promoting the nitrogen cycle in a fish tank.

Aquarium Nitrogen Cycle

The nitrogen cycle is a natural process that occurs in aquariums to convert Ammonia to nitrate with the help of beneficial bacteria. This is a must-needed process in your fish tank to keep it in healthy condition.

A source of Ammonia is required to start the cycling process as it is typically created via fish waste and other biological wastes generated in aquariums. 

Then, various aquarium-specific items may be utilized to dose Ammonia or pure Ammonia might be included. An additional, prominent approach is to ‘ghost feed,’ which essentially allows leftover food to decay and launch Ammonia (keeping no fish in aquariums).

Nitrifying bacteria will execute nitrification, which converts this Ammonia to nitrites (NO2). These nitrates are then converted by another sort of nitrifying bacteria right into nitrates (NO3). 

Nitrates can more easily be eliminated by regular partial water changes. Also, nitrates can be more quickly occupied by aquarium plants and other organisms.

This cycling process typically takes 2 – 4 weeks to be completely established. 

How To Lower Ammonia In Fish Tank

Luckily, there are many ways to lower Ammonia in an aquarium! 

Here are some tips to lower Ammonia levels in a fish tank so that you can enjoy your aquatic friends even more! 

So continue reading if you want to learn how to do just that! 

1. Cycle Your Aquarium

The most vital step to keep your aquarium ammonia-free is to keep the nitrogen cycle fully established in it. In a cycled tank, Ammonia is naturally converted to nitrates which is much less hazardous! 

But in new tanks, the nitrogen cycle is not established because of the absence of beneficial bacteria.

Establish nitrogen cycle

The beneficial bacteria, as the name recommends, are the bacteria that benefit your tank and that really help to reduce the Ammonia in your aquarium.

To boost the beneficial bacteria in your aquarium, you need to cycle your fish tank first.

How to cycle a fish tank (3 ways you can do it)

2. Partial Water Change

When you see any signs of Ammonia in your aquarium, the most basic and straightforward means to reduce Ammonia right away is to do a partial water change.

You need to do a water change of 30 to 50% of the overall water in your aquarium.

The freshly introduced water will not have Ammonia, so it will undoubtedly aid in diluting the Ammonia in your fish tank.

The partial water change is a regular maintenance task of aquariums which is not so tricky at all.

Take a clean bucket that you have never utilized with any chemical or soap. If you remain in doubt about its cleanliness, purchase a brand-new container and keep it apart for fish tank jobs. 

Do partial water change

You will withdraw a portion of water from the tank and refill it with fresh water.

Before adding the tap water to the fish tank, you require to dechlorinate it. 

Once you have dechlorinated the water, switch off all the electric supplies to the aquarium, i.e., turn off the light and the filter.

After that, remove about 30 to 50% of the water from your fish tank using a pipe. You can additionally utilize a siphon to do so; it truly makes it simpler to remove water from the fish tank. 

Now gradually add the freshwater into the aquarium.

3. Improve Your Filtration System

Weak filtration can additionally cause a rise in the ammonia level in your aquarium.

There are several things you can do to boost purification in your aquarium.

Use a filter

If you are not currently utilizing a filter, you should use a filter for your aquarium.

The filter not only maintains the water clean but also houses beneficial bacteria that help minimize the ammonia level in your fish tank.

A HOB filter will work best for those using small tanks of less than 20 gallons. However, larger aquarium owners should consider investing in a more efficient filtration system like a canister filter.

Include one more filter

You know what they say, “The more filters, the merrier!” So if you are using one filter for your fish tank, then it’s time to add another one. 

Improve filtration system

For example, if you have a large tank and currently use a canister filter but want to make sure all those pesky toxins don’t end up in their habitat, too – then supplement with this handy hang-on-back filter!

You can also use products like ammonia blocks, specially made to capture ammonia. Those are really helpful as it helps to deal with the excess ammonia.

Clean the filter

If you observe the water from your filter is not flowing easily, it indicates your filter is blocked. So you need to clean up the filter.

But right here, you should be careful while cleaning the filter because if you clean the filter too frequently and thoroughly, it can cause the loss of all the beneficial bacteria in the filter.

So you should cleanse your filter using the fish tank water – it helps to keep beneficial bacteria in your filter elements.

4. Clean The Fish Tank

If you want to keep your fish tank clean and happy, the water in your home must remain pristine. Regular cleaning will help avoid the buildup of toxic chemicals like Ammonia, which can instantly kill or make life unbearable for those living there. To maintain optimum quality sort through these steps:

Remove unwanted pollutant

Unnecessary impurities like leftover food, dead plant, and fish waste have a high ammonia level in the fish tank.

So you ought to remove such pollutants from the water using a fishnet.

If you found a lot of uneaten food in your aquarium, you are overfeeding. Provide your fish the amount they can finish within 2-5 minutes.

Clean the fish tank

Vacuum your substrate

The substrate is the bottom bed of the tank, so there will undoubtedly be a lot of pollutants trapped in the substrate in your aquarium.

This pollutant can cause a surge in the ammonia level of your aquarium. So cleaning your substrate at regular intervals is vital. A siphon or gravel vacuum can help you do this.

5. Maintain Good Water Quality

The good water quality in your aquarium is the key to success. To maintain it, you need a balanced pH level and adequate dissolved oxygen, which will prevent ammonia buildup ultimately.

Lower the pH of the water

Decreasing the pH of the water does not always get rid of Ammonia from the water directly; however, it makes it much less harmful and provides you adequate time to repair the problem.

If you are using substrates like smashed coral reefs or coral sand, this could be the factor your fish tank water has high pH since it launches calcium that triggers a spike in the pH level of the water.

In an emergency situation, you can do a partial water change to lower the pH of the water.

Have you ever noticed how fish tanks without plants can be a little more boring? If your aquarium prefers some color, consider adding driftwood. The tannic acid released by the wood helps lower the pH of water also! Just make sure all those pretty pieces don’t come treated with chemicals or dyes because they might do more harm than good.

An additional primary method to reduce the pH of the water is by introducing some almond leaves into the fish tank. It functions the same way as driftwood. It will launch tannic acid which helps to decrease the pH of the water.

Related read: How to lower pH level in a fish tank (08 effective ways)

Maintain good water quality

Increase oxygen in the tank

Boosting aeration in the tank can assist in reducing the ammonia level in your fish tank.

The ammonia gas in the NH3 form is toxic for your fish, and also it can be dissolved in the water.

So if you add oxygen to the water, it will increase more dissolved oxygen, thus reducing dissolved Ammonia from the water.

The most basic and most trustworthy means to raise oxygen in the water is by utilizing an air pump. You can also make use of a HOB filter or a spray bar to boost oxygenation.

Related read: How to increase oxygen in a fish tank (11 proven ways)

6. Get A Bigger Tank

If you have a lot of fish in a small fish tank, then this could be the reason your fish tank has a high ammonia level. High fish density is one of the primary reasons that your aquarium water becomes polluted.

Get a bigger tank

So get a bigger tank, or reduce your fish number.

If there are a lot of fish in a small tank, then the fish will certainly produce a great deal of waste that will ultimately create Ammonia. Also, as the aquarium is tiny, the water will quickly get concentrated with the Ammonia.

7. Keep Live Plants

Maintaining live plants in the aquarium is a perfect method to lower Ammonia in the aquarium.

Online plants need macronutrients and trace elements for their proper growth, which they can obtain from waste generated by fish and also leftover food.

So, having live plants in your aquariums is an excellent idea to consume Ammonia produced from waste generated in fish tanks.

Add live plant

Also, plants will add oxygen which is really useful for the fish.

Beginners should start with some Hardy plants like Anubias, Java brush, Java Moss, etc. 

8. Introduce Beneficial Bacteria

If your aquarium is new, then the opportunities are your fish tank has high Ammonia because your fish tank has less beneficial bacteria. But even in an established tank, the nitrogen cycle can be hampered due to reducing bacteria for some reasons like water changes or cleaning.  

The ammonia level in your aquarium may have risen because you mistakenly eliminated the beneficial bacteria from your fish tank.

So, in this case, to enhance the beneficial bacteria immediately, you can add some gravel from the established aquarium right into your fish tank.

The substrate is an area where beneficial bacteria live, so when you add the crushed gravel from a cycled aquarium to your fish tank, it’s like adding these microscopic lifeforms to your own little ecosystem. 

You can likewise make use of filter pads that are used in an established aquarium and end up using them right into their very own filters!

9. Usage Of Neutralizing Chemicals

The short-term method of reducing Ammonia in your aquarium is by adding some neutralizing chemicals to your aquarium.

Use ammonia reducing chemical

The neutralizing additives, do not necessarily eliminate Ammonia from your aquarium yet instead, it makes Ammonia harmless.

You will still need biological filtration to eliminate Ammonia entirely.

What Are The Causes Of Ammonia In A Fish Tank

What are the causes of Ammonia in a fish tank? It’s one question that plagues aquarium owners. 

To combat the problem, you need to know the reasons for Ammonia production in a fish tank in detail. Here are some typical causes!

Generated wastes in aquariums

Waste generation in aquariums is natural and somewhat unavoidable.

In a freshwater aquarium, dead plants and uneaten food generate Ammonia. That’s one of the reasons for the bad smell from fish tank & can kill your fish eventually. 

It’s important to check your aquarium regularly for waste like dead plants and uneaten food. If you find any, remove them using a fishnet!

Likewise, there is some waste entrapped into your gravel, like dead plant leaves. To remove it from the aquarium, you must vacuum your gravel utilizing a siphon.

Usually, you should clean your substrate once in 2 weeks.


This is a widespread problem that causes high ammonia levels in your fish tank.

When you put too many fish into an aquarium, they create waste which ends up increasing the level of harmful chemicals like Ammonia.

A new or larger tank will fix your problem, and you can do some other things to enhance the helpful bacteria in your aquarium too.

Check my article on how many fish per gallon for stocking in the right amount.

Improper Filtration

Poor filtering can additionally create a high ammonia level in your aquarium.

Filters not only remove particles from the water but also provide an area for beneficial bacteria to grow, which will help reduce your aquarium’s level of Ammonia.

So, if you find that the water from your filter is not coming out freely, then it’s time for a cleaning. You can also supplement with one more beneficial bacteria-filled unit to raise those germs!

Less Beneficial Bacteria

This is a ubiquitous factor that causes fish tanks to have high ammonia levels.

Good bacteria aid in removing the Ammonia from your aquarium, and if you don’t have enough beneficial bacteria around, then, of course, it’ll be more noticeable!

Ways to raise beneficial bacteria in aquariums

Include another filter: A fish tank without a filter will be full of nasty stuff.

Aquarium filters are great because they help create an environment hospitable towards beneficial microorganisms such as nitrifying bacteria, which breaks down harmful Ammonia in the water so you can see healthier-looking fish. 

The filter element houses these beneficial bacteria. Therefore, including an additional filter in your fish tank can increase the beneficial germs.

Add more substrate: Just add some gravel and watch your aquarium flourish with beneficial bacteria. The added room will give the good germs a chance at colonization.

Have live plants: Live plants in the fish tank are a great way to reduce Ammonia. They will utilize this waste product and provide them with nutrients while also releasing oxygen which is beneficial for your pet’s health! Plus, plants likewise supply an area for the emigration of beneficial bacteria.

High pH

High water pH can also cause a high ammonia level in your aquarium.

So, decreasing the pH of this environment should help with addressing it! 

Typically when you keep coral reefs or use crushed corals as the substrate, it will result in more alkaline levels than usual because they contain calcium which causes higher pH.

Inadequate Cycling

This is the mistake most newbies make when they are simply starting out with the hobby.

You require to cycle the aquarium before you even put the fish right into the aquarium.

Cycling the aquarium essentially helps to produce the beneficial bacteria in your fish tank.

So, make sure when you put your fish into the fish tank, your aquarium is prepared to remove the Ammonia from the aquarium through the nitrogen cycle.

What Does Ammonia Do In The Aquarium?

Ammonia is a harmful byproduct of fish waste. Therefore, it needs to be converted into something more useful, like nitrates for plants! However, in a cycled tank, Ammonia is converted to nitrates by nitrifying bacteria.

All of the leftover fish food and various other organic matter distributed throughout the tank must also be taken in by beneficial bacteria. This is so they can incorporate right back into our nitrogen cycle!

In return, these microorganisms eat this Ammonia, decreasing ammonia levels in your storage tank as well as maintaining fish from getting ammonia poisoning. 

What Are The Signs Of High Ammonia In The Aquarium

The worst thing to happen in your aquarium is for ammonia levels to spike. It’s not only harmful because it can poison your fish but also because it makes maintaining your tank more difficult and stressful. 

To keep this from happening, I’ve compiled a list of the signs that indicate high Ammonia in an aquarium: 


If you notice that your fish moves around less during the day, there may be a problem. Your fish are supposed to be active during the daytime if they are healthy.

Lethargy is the first symptom of Ammonia buildup in your aquarium.

However, they sleep in the nighttime and move less unless they are a nocturnal species.

Loss of Appetite 

An increasingly inactive fish is a sign that something may be off. If you notice your favorite Aquarium residents going from eating heartily to barely touching their food dish, there could be high ammonia levels in the water, and they need some attention fast!


if you notice that they’re coming on the surface very regularly and gasping for breath, the reason behind this could be high levels of Ammonia in their water, causing them discomfort or even death because it interferes with neurological function over time. 

Gill Inflammation 

Do you know that fishy smell? It’s actually from their gills. So when you notice them with inflamed gills, it means they’re Ammonia toxicity symptoms!

Swelling In The Fins

Fish keepers often see their fish displaying sickly fins and red touches, but what causes this? The raised levels of Ammonia in a tank can be to blame.

Swollen Eyes Or Anus

Fish with a high ammonia level also experience inflamed eyes and anus. It will lead to more critical problems down the line if unchecked!

Final Words

I’m so glad I was able to help you out. You’ll find these methods are great at lowering the levels of Ammonia. However, Ammonia is really unsafe for your fish, so you ought to regularly test water for Ammonia.

Also, ammonia degrees can climb promptly before doing any permanent option that might take some time; you need to perform a partial water change or utilize neutralizing agents in the meantime.

Sujit Modak

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