Do you know how to cycle a fish tank in 24 hours? Yes. It’s possible.

Cycle a fish tank is challenging. You will see many ideas and methods. Genarally, it is a time-consuming process. It takes four to six weeks to complete the nitrogen cycle naturally.

But is it possible to cycle a fish tank in 24 hours? The answer depends on your experience. If you are an experienced aquarium keeper, you can cycle a fish tank in around 24 hours using some tactics.

You should be familiar with the fundamentals of aquarium keeping. Knowledge about the nitrogen cycle is essential, as well as the water testing ability. If you are a newbie, you probably can’t manage the risk.

So, the aim of the post is to give you a clear idea of ​​how to cycle a fish tank based on my experience.

What Does It Mean ‘Cycle A Fish Tank’?

An ongoing fish tank collects waste. Some waste contains toxic ammonium components, which can be fatal to fish. But beneficial bacteria can break down toxic ammonium components into harmless components. This process is called the nitrogen cycle.

Generally, many natural things contain beneficial bacteria. But unfortunately, new tanks don’t have enough bacteria. New tanks refer to newly established or recently cleaned fish tanks. Those lack sufficient beneficial bacteria to break down the toxins.

Then who protects your fish from ammonia? The process of increasing the number of beneficial bacteria in a freshly prepared fish tank up to the required level is called ‘the cycle a fish tank.’

What Are The Methods To Cycle A Fish Tank?

01. Fish-Less-Cycle

Aquarium owners frequently use the fish-less-cycle technique. Here, we kick-start the natural nytrogen cycle using liquid ammonia. Ammonia is the food source for benificial bacteria. They work on ammonia and create nitrite. Also increases their number rapidly.

We should wait for the good bacteria to multiply naturally. Gradually, the ammonia level goes down while the nitrite level increases. Finally, the nitrite level also goes down, and the nitrate level increases.

A completely cycled fish tank is free of ammonia and nitrate; nitrite is below 40 ppm. We need to be patient for a few weeks until this happens.

02. Fish-In-Cycle

This method uses fish poop & pee of living fish as an ammonia source, but it is not a good practice as fish is always a risk. Ammonia and nitrate levels fluctuate in the pre-cycle period. Their fore fish can die or be damaged in between the process.

Today I aim to discuss the instant cycle method, not the fish-in or fish-less.

03. Instant Cycle

How to instantly cycle a fish tank? For that, we have to add established live good bacteria colonies. You can purchase bacteria or can find them. And should provide an energy source for them.

Usually, after one day tank will be cycled. But before adding fish, we should check ammonia, pH, nitrate and nitrite. You can start stocking lightly after one day. Go through the below steps carefully. Each step is essential.

Steps To Instant Cycle: How To Cycle A Tank In 24 Hours

Step 1: Arrange The Tank, Adjust The Water Quality, Aeration And Heating

To begin, arrange the fish tank as desired. Fill the water, and add the gravel, decorations and other required accessories.

Water suppliers add chlorine to tap water, that act as a bacterial killer. We have to remove chlorine before starting the cycle process. Use a water conditioner to remove chlorine.

Good bacteria are preferred a 7 to 8 pH range that encourages their biological activities. So, maintain that pH level. It is an advantage for the instant cycle.

Highly oxygenated water promotes the growth and reproduction of beneficial bacteria. I used to add an extra air hose and air stone to enhance the aeration process.

Step 2: Add A Cycled Filter

Next, find an already cycled filter from a healthy aquarium. A cycled filter is a filter that is currently in a cycled fish tank. It contains a large number of living bacteria that can degrade nitrogenous compounds.

The found filter should install the tank we’re going to cycle. The cycled filter may appear ugly and old but should keep without any cleaning attempts.

What type of filter is more suitable for our phenomena?

Canister filters contain bio balls and ceramic rings that work as biological filter media. Hang-on back filters hold a significant amount of biological media. Sponge filters carry many beneficial bacteria with their sponge. The above filters are optimum to fulfill our requirements. Under gravel filters or corner filters are not recommended.

How do you find a cycled filter?

Usually, I find that kind of a filter from my tank collection as I have many fish tanks. But you may get in trouble if you have no more fish tanks. No more tanks mean no more filters. A better solution for that problem is to ask your friend or a local pet store.

You are lucky if you have few friends engaged with fish keeping. Probably you can share the filters. Also, some pet store owners have extra filters to use in some emergency cases. Try and find out.

If you can’t find a cycled filter, go for cycled filter media.

Sometimes though you try to find it, you can’t. Then do we have anything to do?

Yes. We can add some cycled filter media without adding the whole filter. Bacteria abound in bio balls and ceramic rings. Adding those will boost your new tank cycling process, but it takes a few days.

Let me tell you a pro tip that I do. Some of my tanks have sponge filters. When I need to cycle a tank quickly, I remove an old sponge from a sponge filter. Then I soak the old sponge in the new tank allowing bacteria to enter it. Try this yourself.

Is it safe to add such a filter to your new tank?

It would help if you verified that your friend or pet store tanks are healthy.

Step 3: Add A Cup Of Old Gravel And A Sufficient Amount Of Rotten Fish Feeds

Gravel in a cycled fish tank is a good source of beneficial bacteria. As the next step, add a cup of old gravel and mix it evenly with existing gravel. You can add an extra cup of gravel if your tank is above 20 gallons. 

Why rotten feeds? Bacteria need an energy source such as ammonia. They can eat ammonia that produces by rotten feeds.

Step 4: Add A Bottle Of Bacteria And Add Fish

Bottled beneficial bacteria are helpful to cycle a tank instantly. Several companies produce beneficial bacteria bottles, find the best one and pay attention on expire date.

After 24 hours, measure the water quality parameters. The theory is zero ammonia and zero nitrates. If the reading is accurate, you can stock fish lightly.

STOCK LIGHTLY! Add some hardy fish as one fish per 10 gallons. Now we are not done. We are in a danger zone. Ammonia, nitrate and nitrite should measure twice daily until they are stable. When nitrate is up, 30% of the water should change.

Extra Tips: How To Cycle A Tank In 24 Hours

Season Your New Filter In A Old Tank

Finding an old filter may be difficult so you can try the method below. Install your new filter in a cycled fish tank. Let it operate for more than seven days. The filter will collect sufficient bacteria during that time. Sometimes, my friends use my tanks to season their filters.

Is It Essential To Cycle A Fish Tank?

Suppose you bring a new fish tank and setup it up at home. Do you think stocking fish is the only remaining thing? No! You can’t stock fish at once because you don’t have beneficial bacteria as it is a new tank.

Without sufficient beneficial bacteria, the nitrogen cycle is incomplete.

No nitrogen cycle means ammonia is collecting there if you add fish. It can cause fish to die. That is why cycling a fish tank is essential.

Wrapping Up

Cycling a fish tank before adding fish is essential. It usually takes a few weeks to cycle a fish tank naturally. But we can do some pro tips to reduce this period. The leading theory is to place the beneficial bacteria colonies in the fish tank. Bacteria are available in pet stores, old filters and old gravel. After putting them in our tank, caring for them is essential.

Closely inspect the water quality to check how bacteria are working. After one day, add a hardy fish if the water quality is good. Do the water testing frequently. Now you are aware of how to cycle a tank in 24 hours.

Happy fish keeping.

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I am Bruce Daniel Holgate from Los Angeles, the founder of, environmental scientist and content writer. Researcher and hobbyist in aquarium keeping and fish breeding with 20 years of experience. I'm willing to share my knowledge with you all.


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