How to Cycle a Tank in 24 Hours? 5 Steps to Instant Cycle

You’ve got your tank. You’ve bought all the pretty decorations. Now you want to go and buy your first fish – but the aquarium needs cycling first. When you’re so eager to start your new hobby, you’re probably wondering, “How to cycle a tank in 24 hours”? Is this even possible?

Cycling a tank in a day is possible, but it’s not easy – especially if you’re new at the fishkeeping hobby. 

Completing a quick nitrogen cycle requires lots of knowledge and some preparation. Luckily, with a few tips and tricks, you might be able to complete it.

Here’s how to cycle a tank in 24 hours in 5 quick steps!

How Do You Cycle a Tank in a Day?

Tank cycling is a necessary process during which a tank gains fully functioning biological filtration and you need to complete it before you add fish. If you skip the tank cycling process, you’re risking the death of your aquarium inhabitants.

Even amateurs know that cycling a fish tank takes a long time. In fact, this process can take up to 10 weeks! This alone is enough to make many people give up on their hobby before properly starting it.

Luckily, it is possible to cycle the freshwater tank much faster. All you need is proper tools and a lot of care. Still, there might be a reason why you shouldn’t do this – but more on that later on.

Here is how to cycle a tank in 24 hours in 5 steps:

Step 1

The first step is to make sure everything is set properly. What you need to do is arrange the tank according to your liking. Place the substrate, add the decorations, and make sure everything is set.

If you wish to add something later on, you can, but this comes with its own risks. As such, I’d make a list to make sure I don’t forget anything.

Next, add the water. You can use both tap water and RO/DI water, but depending on your choice, there might be a few additional steps.

Using Tap Water 

If you’d like to add tap water, you can. However, tap water contains chlorine as a disinfectant. 

While chlorine is known as a bacterial killer, it is toxic to fish, especially in larger amounts. As such, you must get rid of it beforehand.

The easiest way to dechlorinate water is to pour it in a bucket and let it stay for 24 hours. This way, the chlorine will evaporate. 

Another solution is to use a water conditioner that will get rid of chlorine and make the water safe for fish.

Step 2

Next, you want to make sure the water you’ve used has proper water parameters – not just for the fish you plan to add, but also for the beneficial bacteria that needs to grow. 

In general, you want to make sure the pH levels are between 7 and 8. This is the most important step, as anything above or under these parameters can be toxic.

This is especially important if you’re planning on having an instant cycle. For the good bacteria to thrive, parameters need to be as close to perfect as possible.

Another important thing to keep in mind is the oxygen level. The water needs to be highly oxygenated to promote the growth of good microorganisms. 

A good way to achieve proper oxygenation is to use an air hose or an air stone. This will ensure the water is as fresh as possible.

Finally, you need to think about water temperature. You want your water to be between 70 and 90 degrees Fahrenheit. This will help the reproduction of bacteria.

Step 3

The next thing you need to do is add a filter – and this is where things get tricky. 

A new filter won’t do. You need to get an already cycled filter. In other words, you’ll need a filter that has been used inside a healthy, established tank. 

A cycled filter is important as it contains a large amount of good bacteria that can help with the nitrogen cycle. These bacteria help maintain proper nitrate levels with the help of oxygenated water.

Once you’ve found a cycled filter, don’t clean it. I know it may look old and dirty, but that’s the point. You need everything it carries to ensure you have a good ammonia source and that your cycle is completed quickly. 

Where to Find a Cycled Filter

The best option would be to use a filter from an old, established aquarium you have. However, this only works for experienced fishkeepers who already have a tank. If you’re new in this hobby, this obviously isn’t a good choice for you.

The next best choice would be to ask a friend who also has a tank. They might be able to borrow a filter they use inside their tanks. Of course, this only works if you have a friend in the hobby, or if they have a spare filter to use in the meantime.

Finally, you can always ask a local pet store if they are open to gifting or selling you one. Just make sure the store is reputable, as the existing tank needs to be healthy. 

If the found filter has been in the tank with sick fish, chances are you’ll contaminate the existing tank, and this likely isn’t what you want. 

If you aren’t certain about the quality of the filter and whether the filter was in a healthy aquarium, it’s best not to risk it.  

Using Cycled Biological Filter Media 

It’s not always possible to find a proper filter. If this is the case, don’t panic. You still have options. 

Instead of using a cycled filter, you can use cycled filter media. What does this mean?

A number of beneficial bacteria can be found on many parts of the tank. A good place for microorganisms is the filter’s sponge. You can simply remove an old sponge from a used filter and place it into the new tank.

Don’t worry, you don’t need to actually replace the parts of the new filter. However, this might prolong the cycle time for a bit, as the bacteria will need more time to grow and spread this way. Simply soaking the parts into the water will do the trick.

Other filter media you can use include ceramic rings and bio balls.

Step 4

Next, you want to make sure your bacteria has a good food source. There are a few tips and tricks for this.

The step you’ve probably seen everywhere is to use substrate from an established tank and combine it with the new one. If you have a larger tank, you can add a bit more substrate than you would for fish alone. 

This substrate likely contains lots of fish waste, which is an excellent food for bacteria that control the nitrite level. 

You can also add a bit of fish waste, if you can get your hands on it. While there might be some fish species that will eat fish poop, fish waste is also a great food source for bacteria.

However, this is probably challenging, so I would skip it. While you can use water from another tank, there is no guarantee how much waste can be found in it.

Instead, you can add a bit of rotten fish food. 

In a standard tank cycling process, you’d add a bit of fish food and leave it inside for weeks. However, as you wish to speed up this process, you want the food to be rotten before you put it into the tank. 

Rotten food is a good ammonia source that bacteria will eat.

Step 5

Finally, you want to use bacteria from bottles. Yes, you’ve read that correctly. In fact, this might be the most important thing if you want to cycle your tank quickly.

Many pet stores sell beneficial bacteria bottles or bacteria supplements. These can help in many different ways, but one of the most important benefits is they can help maintain good nitrite levels. 

Add a bottle of bacteria to your freshwater fish tank. Leave it for 24 hours, then check the water parameters.

The required levels for adding fish are zero nitrates and zero ammonia. If the parameters show this, it means you can add the inhabitants to your tank. 

Just remember – there are limits to how many fish you should add per 5-gallon of water!

Should You Cycle a Tank That Quickly?

Now that I’ve given the answer to the ‘How to cycle a tank in 24 hours’ question, it’s time to answer another important one: Should you do a quick cycle in the first place?

Cycling a tank in 24 hours isn’t really a good practice. While knowing how to complete it is a beneficial practice, you should use it for emergencies only, and there are several reasons behind that.

First off, there are many risks associated with the quick cycling process. The cycled filter or filtered media might be contaminated, and you’re risking the health of your fish.

Not just that, but perhaps your water testing kit isn’t working properly. This might result in wrong water parameters.

While this can happen during a regular cycle, as well, the chances are much higher during a quick cycle. Don’t forget that you cannot know whether the parameters are good with the naked eye only!

Finally, this isn’t a good long term solution. When you do a cycle in a day, you cannot be certain that you’ve achieved proper balance. Your ammonia amount might spike after a few weeks, and this is never a good thing to happen.

When Is a 24-Hour Cycle a Good Thing?

There are certain situations in which a quick cycle is certainly the best option for you. In fact, these cases are why I think everyone should know how to cycle a tank in 24 hours, even if they never end up using this knowledge!

Here are some occasions that might require instant cycle:

• Contamination of the entire tank. Whether we’re talking about illnesses or harmful ammonia levels, sometimes our tank can become so contaminated that cleaning the tank without getting the fish out can no longer work! The best solution is to remove all the water and start anew.
• Outbreak of parasites or harmful bacteria. Such scenarios require quarantine tanks, but you don’t have several weeks to wait for your tank to cycle.
• Your pH levels have started to rise uncontrollably. This can be caused by something harmless like lack of live plants or by something much more malevolent. Either way, you need to start from scrap – but you might want to try a few methods for lowering pH levels first.
• Your pH levels have started to drop uncontrollably. Same as with too high levels, low levels are not a good sign, and methods for raising pH levels are not always successful.
• The ammonia levels are spiking the moment you’ve added inhabitants to your new fish tank. This means something is terribly wrong and you shouldn’t leave your fish inside such water for longer than absolutely necessary.

No one wants these situations to happen, especially as they can be deadly to your fish. The good news is that an instant cycle can help you save your tank. This is the main reason why I wanted to share these steps with you.

Final Words

There are a few scenarios that might require you to know how to cycle a tank fast. However, you shouldn’t do an instant cycle lightly, as it carries many risks. 

Whether you have a freshwater or a saltwater tank, cycling is a necessary process that can make a difference between life and death, at least for your fish. You should never skip it.

Don’t forget that the use of filters is necessary even for a cycled tank. Filter and proper maintenance are the only ways to keep your tank healthy and your fish happy. 

Check your ammonia levels regularly and make sure all the parameters are in order. If you do, your fish will thrive!