How To Cycle A Fish Tank Fast? Ultimate Guide

If you want to do a fish cycle fast to keep your fish tank healthy and toxin-free, then you are at the right place. Fish tank cycling is essential for turning toxin elements into less harmful. That ensures the better health of your fish and other living creatures of your fish tank.

In this article, I am about to explain how to cycle a fish tank fast, why it is necessary, and other relatable topics that you need to know.

What Does the Cycle a Fish Tank Mean?

Cycle for fish tank refers to the nitrogen cycle of a fish tank. It is a way to convert harmful ammonia into nitrite throughout the process. Let me explain further.

All the waste caused by fish poop, waste food, fish urine turns into ammonia. And that is dangerous for fish health.

There is a bacteria that grows in the fish tank called Nitrosomonas. And, Nitrosomonas converts ammonia into nitrite. However, nitrite is more toxic than ammonia. Therefore, you need something else to get rid of that.

Fortunately, other bacteria convert nitrite into nitrate called Nitrobacter. And nitrate is less harmful than ammonia.

As a result, your fish tank remains safe and balanced for keeping better health of your fish and other aquatic lives in the fish tank.

Suppose your fish tank has 40 part nitrate per million (ppm) that states as a safe amount. However, you should keep it under 20 ppm for sensitive fishes.

What Happens If you don’t Cycle Your Tank?

If you do not cycle your tank, there will be no conversion of ammonia. As a result, your fish tank will be toxic day by day. Therefore, fish would die or get attacked by severe diseases.

So, it is necessary to do a cycle to keep your fish alive and remain healthy.

How Often Should You Cycle your Fish Tank?

There is no exact period for that. But, changing 10 to 25% water every one or two weeks is a good habit. However, it depends on your fish tank size and fishes on the tank.

If you have more fish, then it will create ammonia quickly. Therefore, you must act based on that fish amount and tank size.

How Long Does it Take to Cycle a Tank Fully? 

Fish tank takes time to cycle fully. It depends on tank size and the existence of fish. Let’s discuss that further.

This cycle usually requires six to eight weeks to complete. After setting up a fish tank, when you add fish food, food waste will be produced there. So, it will take a few weeks to grow beneficial bacteria.

You have to test the water to see the nitrate level. If it is somewhere between 0 to 50 ppm, you are on the right track.

However, the Nitrogen cycle takes 6-8 weeks to complete. And according to your fish tank size, it may take a few days here and there. And you have to act differently according to your tank size.

Can You Cycle a Tank in 24 Hours?

Some beginners claim to cycle fish tanks in just 24 hours. However, it is the last thing you should do to your fish tank. This is because the process converts ammonia into nitrate takes time. You can boost the process duration, but it is impossible to be wholly done in just 24 hours.

You will see no ammonia or nitrite in your tank or a reasonable amount if you do so because those are invisible. Only by testing correctly can you measure the amount.

So, doing a cycle in 24 hours ain’t going to happen. Therefore, your fish tank becomes unsafe for your fish and other aquatic life’s health.

However, since there are few ways to do that fast, you can try those. As a beginner, I suggest you follow the proper course of the fish tank cycle.

How Do You Cycle a Fish Tank Fast?

Although there are no ways to do the cycle overnight, you can speed up that process through basic rules. And, the beginner often mistakes on these basics. As a result, cycling a fish tank takes more time than it should be. So, first, do the basics right.

Basics You Should Correct.

1. Dechlorinate

Caroline is suitable for drinking water. It makes water safe by killing harmful bacteria. Therefore water becomes safe for drinking.

However, choline is harmful to fish health and beneficial bacteria.

So, the first thing you have to do is, dechlorinate the water before adding it into the tank. Otherwise, it will kill the bacteria you need to complete the nitrogen cycle.

You can do that by adding chemicals. You check here to find the best product to dechlorinate water.

2. Maintain pH Level

It is the most basic rule of aquarium fish keeping.

Usually, bacteria grow on pH level 7 or above. But, regular drinking water has a pH level of 7 or above. So, you can use that.

However, you should test the water pH level to ensure it is safe for your fish tank. You can get an API test kit. That will measure the pH level. Also, it will later use to measure nitrate, ammonia, and nitrite level.

3. Keep the Temperature at a Level.

Those beneficial bacteria grow at a certain temperature level. Usually, warm water is better for their growth. So keeping temperature 80 to 87 degrees Fahrenheit is the standard temperature for bacteria. It will speed up bacteria growth.

However, never go above 87 degrees. It can be harmful to your fish.

4. Increase Oxygen Level

Oxygen is necessary for all living beings. Lower oxygen level is stressful for both your fish and beneficial bacteria.

You can use an air pump to keep the Oxygen flow at a decent level.

5. Keeping Filter Running

If there is no fish, some of you think there is no need for a filter. But, bacteria colonies usually grow around the sponge or the filter floss.

So, if you turn off the filter, the Oxygen level will decrease, and eventually, bacteria will die.

Therefore, you should never shut off the water filter.

Get a Filter Media From an Old Fish Tank.

Since you have done the basics, let’s do some processes to speed up fish tank cycling.

You already know bacteria grow near the filter. So, if you get filter media from an old fish tank, it will speed up bacteria growth. You do not need to wait for growing bacteria before starting the nitrogen cycle.

Your fish tank will directly jump into the nitrogen cycle process. Because you already got the bacteria in your tank.

However, getting filter media from another tank can carry harmful diseases into your fish tank. So always get it from a trusted source. 

Add Beneficial Bacteria to Your Tank.

Another way to complete the nitrogen cycle is by adding bacteria. You can get those beneficial bacteria in the market. Just get a bottle or more according to your fish tank size. Then, pour that into your fish tank.

Since you got the bacteria, it will start right from the nitrogen cycle. But, I suggest getting bacteria from a trusted source.

You can get Fritz nitrifying bacteria for freshwater aquariums.

Few Other Ways for Experts

If you are a beginner, you must follow above mentions process only. But, if you are already familiar with fish tank cycling, you can follow these processes too.

Season a Filter

If you have an established fish tank, you can install another filter beside the existing filter. And, when your new filter grows bacteria, you can transfer that to your new fish tank.

Get Some Plants

Plants are commonplace for bacteria to coat. Therefore, adding some plants to your fish tank will speed up the cycle process. However, it requires a lot of attention.

Because plants can also grow some harmful bacteria, algae, and beneficial bacteria, if you do not know how to get rid of them, there is not necessary to apply this procedure.

Add Gravel

Also, adding gravel from the existing fish tank will complete the nitrogen cycle fast because beneficial bacteria coat with gravel.

How to Know If your Fish Tank is Cycled?

After the cycle starts, you will see ammonia levels decrease in your fish tank. You can measure that via an API test kit. Also, you will see increases in nitrate levels.

You have to wait for a few weeks to see the result.

In the meantime, you have to test the water to measure the ammonia, nitrite, and nitrate level.

When you see 0 ammonia and nitrite, you can say the cycle has been done. Also, make sure to keep the nitrate level at 25 parts per million or below at the beginning.

So, you can add fish into the fish tank at this point. It will be safe for your fish health and growing plants inside the tank.


That was all about how to speed up the fish tank cycle. If you do this right, it will benefit fish health and keep the fish tank healthy. However, doing something wrong can cause severe damage to your fish tank. Therefore, you have to follow every single process. Never overdo anything as a beginner unless you know what you are doing.

Related Posts:

Arif H Fahim

Welcome to PetFishTank! My name is Arif. I make an effort to publish educational articles using my many years of expertise as a fish owner.

Recent Posts