Before the excitement of getting the long-desired reef tank gets you, you should think of the preparation first because you cannot just buy a tank and throw some coral, fish, sand, water, and rocks in it. If that is the case, be aware because you need some learning about how to cycle a reed tank.

There are 3 widely used techniques to cycle a reef tank: with fish, without fish, and bacteria starter. Remember to get a water test kit before you dive into cycling your aquarium because you will use it regularly in the future.

While discussing the methods, I will also shed light on the nitrogen cycle and the mentioned tests for you to get a proper understanding of the entire system.

What Is Nitrogen Cycle?

It is the process where bacteria turn ammonia into nitrite with less toxicity. Afterward, additional bacteria will split the nitrite down to minimize the toxicity even more. But it is not a one-time procedure.

You have to change the water regularly, combining it with a protein skimmer and different filtration methods to keep the nitrate quantity in check.

Why Is It Important To Cycle Nitrogen?

That is a common question from new reefers. And it is pretty logical too. Nitrogen is one of the fundamental components of life. Why would anyone have to cycle it?

The answer is here: the mini water environment in your home is not an ocean. The reason for nitrogen cycling is similar to that of reef salt mixing, reef lighting, and nutrient export – replicating the organic world in that enclosed environment in your living room.

How To Cycle A Reef Tank

Reef Tank Cycling In A Nutshell:

  • Start with a clean and properly sized tank.
  • Add live rock to the tank to provide a surface for beneficial bacteria to grow.
  • Add a small amount of live sand to the tank to provide a surface for bacteria to grow.
  • Fill the tank with dechlorinated water.
  • Install and set up all necessary equipment, including a heater, filter, and lighting.
  • Test the water regularly and perform water changes as needed to maintain water quality.
  • Slowly introduce hardy fish and invertebrates to the tank over time.
  • Monitor the tank closely and make adjustments as needed to maintain a healthy environment for the animals.

How To Cycle A Reef Tank? [3 Methods Explained]

Come to the main part now. I already mentioned the methods and the essentials. Let’s get to them straight below.

1st Method: Tank Cycle With Fish

It is the most common among the three methods. However, you have to be cautious because nitrite can kill fish upon reaching toxic levels. If your tank is small or medium-sized, you will only need a couple of small fish.

Some individuals like to have clownfish, chromis, and damsels because they are cheap, available, and hardy. But sometimes, they can get aggressive, especially if the tank is small.

Timeline: 3 weeks at the minimum and 6 weeks at the maximum

Benefit: Easy to do and not costly

Downside: Time-consuming process

2nd Method: Cycling Without Fish

You have to put any ammonia-rich source like shrimp or fish food in the water in this process. They will produce ammonia by decomposing. Alternatively, you can add pure ammonia free of surfactants, detergents, or perfumes.

The general rule of measurement here is that if your tank has 10 gallons of water, you will need 5 drops. But reduce that to only 3 drops per day after detecting the nitrite levels.

The duration and pros and cons are the same as the first one.

3rd Method: Reef Tank Cycle With Bacteria Starter

It is the quickest method to cycle a reef tank. You can use Microbater Start, Dr. Tim’s One and Only, and Fritz Turbostart to do it. They are the most popular among the current cycling products in the market. They work fast and will prepare your tank in no time.

Timeline: 24 hours (more or less)

Benefit: Fast and effective

Downside: The bacteria population may become unstable, causing nitrite and ammonia to increase. It is safe to keep a small number of fish. My recommendation would be to wait for several weeks before adding coral. That would give buy some time for bacteria levels to stabilize.

What Are The Testing Processes?

If you think you are done when you add ammonia or use the bacteria starter, you are wrong, amigo. It is a continuous process. The next part of the process requires you to perform some tests to monitor your tank water and environment. Let me tell you how they help you do that.

  • Ammonia Test: Perform this test daily until the ammonia level drops. Once it does, start testing the nitrite levels while carrying on with ammonia.
  • Nitrite Test: Perform this one daily too. They usually tend to rise fast and fall dramatically. Once they fall, start with nitrate while keeping up with these do. Continue to carry out the three tests until nitrate levels range between 0.025 ppm and 5.00 ppm and the other two reach 0.
  • Water Change: When the three elements reach the mentioned ranges, change around 10% of your tank water. Then it should be safe enough to bring one or two additional tiny fish into the tank.

I recommend bringing only one or two fish each week after cycling your new reed tank. Introducing more fish will increase the bioload. You have to take it into account to avoid sudden deaths of fish.

Keeping the light off in the beginning weeks also helps keep algae growth at bay as they live on light and nitrates. However, remember to keep it on for at least 10 to 12 hours for the best outcome.

Additionally, if you change the water regularly and keep tank cleaners like shrimp, snails, and crabs in the tank, they will prevent the algae from repopulating.

What To Do When The Cycling Process Is Entirely Complete?

Once you have cycled your tank successfully, you will not have to recycle it. Nitrite and Ammonia levels should stay at 0 ppm. But if ammonia is there in the water, the fish may die soon, which is why you have to perform the tests even after the cycle completes.

When you detect ammonia, you can reduce it back to 0 by changing the water partially or using neutralizing agents.


  • You can also use dry ammonia chloride as a great ammonia source for recycling.
  • Creating a bacterial culture works effectively to speed up the cycling process. That is something to keep in mind.
  • When ammonia rises suddenly, check the tank filter. See that it is functioning right, and the tank gets sufficient gas exchange.
  • You can bring mollusks and crabs into the tank to cycle it. But unlike fish, they will not produce much waste, which will lengthen the process.


  • Although nitrite and ammonia are essential for cycling your tank, their levels should be zero once you add fish.
  • You may want to overfeed your fish out of care and love. But that will only increase the ammonia levels.
  • Never try combining cycling with fish and without fish because getting the temperature high while adding more ammonia can kill your fish. You have to choose either of the options beforehand.

Final Words

Starting a reef tank is a fun and exciting hobby. That can make keeping patience hard for you. But do not let it get the better of you since you have learned how to cycle a reef tank and its importance.

If you do not cycle your tank properly before bringing fish and coral, they cannot survive. Cycling will help prevent that and maintain a healthy environment for your water buddies.

Best of luck, and thanks for reading!

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