When it comes to setting up the perfect aquarium, an aquarist goes through thousands of thoughts. It is not easy to set up an aquarium that easily, especially when it comes to saltwater tanks, unless you are super pro at it. On top of that, if you want to step ahead for a FOWLR tank setup, you need to know all about it beforehand.

Setting up a FOWLR tank is very challenging because it needs so many things for setup and filtration systems. You must also maintain proper light setup, substrate, live rocks, and more. You can also keep fish in there, but not all kinds of saltwater fish will be fit for such a tank.

In this article, I have discussed everything you need to know about setting up a FOWLR tank. So make sure to read the entire article.

What Is A FOWLR Tank?

FOWLR is actually an acronym. Its full form is fish only with live rocks. It is one of the 3 types of saltwater tanks. And the other 2 are fish only tanks and reef tanks. So you can tell why a FOWLR tank is different from others.

One of the main elements of the FOWLR tank is live rocks. Live rocks help your tank environment with various beneficial bacteria, as bacteria have the ability to break down ammonia and keep the tank environment cleaner.

Then it comes to picking various saltwater fishes. The setup is much like a freshwater fish tank. And learning how to set up a FOWLR tank will take you a step ahead in learning about reef tanks.

What Can Go In A FOWLR Tank?

Before you even learn about what you can put in a FOWLR tank, you should know what tank size would be ideal for it. Of course, you can choose any tank size that seems convenient to you. However, there are pros and cons for each size.

While the smaller tanks do not take up a huge space, with so many saltwater elements inside, the environment can easily become toxic if you do not maintain them regularly. On the other hand, larger tanks are not space-savvy, but they are quite safe when mixing several tank elements because they don’t easily cause any harm.

Filtration System And Protein Skimmer

A good filtration system is essential not just for tank fishes but for all other living organisms in it. In fact, if you ensure the best filtration system, you can easily accommodate more fish than you thought you could have.

So when it comes to the filtration system for a FOWLR tank, you must pay more attention. And for such a tank, a high-quality filtration system is more appropriate. The best thing to do is to choose a wet/dry filter.

On the other hand, having a protein skimmer is not mandatory. But it can help you maintain your tank’s water quality and control nutrients level. And it is an affordable option, but try not to go for the cheapest available option. However, when choosing a protein skimmer, make sure to pick one that will process at least 1.5 liters of water volume every hour.

Water Circulation (Pumps And Wavemakers)

Some might tell you that water circulation is not really an important factor for a FOWLR tank setup. On the other hand, I believe water circulation is something you should prioritize as much as the filtration system.

With enough water circulation, it will help keep algae from taking over the tank. Besides, with enough water flow, it can easily move the wastes away toward the rocks and keep the tank environment cleaner. But how do you ensure accurate water circulation?

Well, for that, you can get water pumps and wavemakers installed. There are many types of them available in the market. You just have to get one that is compatible with your fish tank.

Lighting System

If you know how a fish only tank works, you would know that a lighting system is not very important or exactly vital there. The same goes for a FOWLR tank. However, setting up a lighting system can be a basic choice. 

But with the right lighting system in the tank, you can enhance some specific algae growth and help the microorganisms residing in the tank. But what kind of lights work best for a FOWLR tank?

Usually, fluorescent lights are said to be an excellent choice for such tanks. But to many tank owners, they are an expensive choice. But you can also choose any 1-3 watt powered light for every gallon of water in the tank. The problem with high-powered lights is that you have to install a fan to ensure the water temperature and other things remain cool enough.

But as you stock your FOWLR tank over time, many things change in the tank environment. And at some points, the lighting system becomes something you should pay attention to. So you must set it up according to your tank environment to ensure the best for fishes and other microorganisms.

Water Source And Mixing Saltwater

What is your source of water for the FOWLR tank? This is important because tank water is one of the vital things that will either help the fishes and other organisms live or kill them. So you must ensure good-quality saltwater for your tank.

You can either mix saltwater or buy the water from aqua shops. And if you are mixing the saltwater at home, make sure the salt has dissolved properly before pouring the water into the tank. Here is how you can mix saltwater at home:

Pour some water into a bucket and mix salt until the gravity reaches between 1.022 and 1.026. After that, pour the mixed water into the tank. Repeat the process until you have enough water in the tank.

Live Rock

The whole thing about having a fish only with live rocks tank is having live rocks in the fish tank. So make sure you have plenty of them, but try not to overcrowd the tank with too many of them. And the best way to know you are adding enough live rocks is to know the quantity.

For each gallon of water in your FOWLR tank, you can add 2 pounds of live rocks. In a reef system tank, the amount is usually a little higher. Because when you have a reef tank set up, you get more nitrogen waste loaded on them.

But it is essential to choose rocks that also look good and can enhance the appearance of the tank set up. Sometimes, when living organisms die, they create a mess on the rocks. So watch out for that too.


You can add various substrates in your FOWLR tank, such as sand, corals, anemones, etc. Usually, the recommended layer thickness for a fish tank is about 1-2 inches. However, that also depends on your tank type, size, and the number of fish you have kept.

For example, if you have a larger tank filled with larger livestock and fish, you can add more substrate and can have thicker layers. And you should also know that the layer does not need to be perfectly flat. But make sure to cover the entire bottom area of the tank so that the glass is no longer visible.

For some FOWLR tank owners, the cost of having sand or similar substrates seems a bit unnecessary. So if you want to reduce the cost, you can just add crushed shells and corals.

Tank Cycling

Before you reach the final stage of your FOWLR tank setup, you have to wait for the tank to cycle. It is the process the tank goes through before it becomes ready to have fish in it. But how does it work?

Well, if you have completed all the previous steps, you will notice that your tank water now has a smell. Yes, it might seem unpleasant at this point, but it is not permanent. So don’t worry.

Gradually, within 2-3 weeks, the tank will begin to lose the smell. And that’s when you know the tank has reached the peak of its cycle. So make sure to test the ammonia and nitrites levels in your tank water. If the reading says 0, your tank has reached its full cycle and is ready to have fish and other tank animals.

But you should also know that the cycling period is not the same for all tanks. While some may complete the cycle in a week or two, others may take several weeks. So the best way to keep track of that is to test ammonia and nitrites regularly.

Fish Selection

Finally, it comes down to selecting the right fish for your FOWLR tank. You can add various saltwater fish, such as clownfish, eels, lionfish, or anything that seems suitable for your tank. But most aquarists advice starting with clownfish at first.

Even if you did not own a FOWLR tank before, clownfish is one of the easiest ways to start something new as they are not a hassle to maintain. On top of that, clownfish are pretty colorful and vibrant. They are also among the small yet most beautiful saltwater fish you will come across. Depending on your budget, you can purchase different species of clownfish from any aqua shop.

But make sure not to have more than 1 or 2 fish at first go. And if you are having more than one clownfish, you must get two from the same species. You can use the following method to add fish to the tank.

  • Put the bag of fish into the tank without opening it.
  • Let it float in the tank water for around 10 minutes.
  • Take out the bag, open it, and pour a cup of water into it. Or, you can pour the bag of water and fish into a larger container and add a mug of tank water.
  • Then wait for 5 minutes.
  • After that, add a few more cups of water and wait some more time.
  • Finally, gently let the fish out into the tank water. It might take some time for the fish to adapt.

Make sure to change your tank water from time to time to ensure a healthy tank environment. Change 5% of the water every week and about 10% every fortnight. It will help you recover the lost minerals.

But do not, under any circumstances, add freshly mixed saltwater to the tank. Also, clean the tank glasses to remove algae and other buildups to help your tank appear more beautiful.

Do I Need A Sump For A FOWLR Tank?

The sump is part of the fish tank where all the necessary equipment and accessories are kept. Most aquarists prefer remote sumo as it helps clutter all the visible equipment from the tank and enhances its view. But do you need one when doing a FOWLR tank setup?

Not really. A sump is not mandatory for setting up a FOWLR tank. However, you can add one to keep the distracting equipment tucked away and also to enhance your tank’s water volume. And not only that. Though mild, a sump also helps with the tank’s filtration system and increases stability.

But, as the same thing can be achieved using the filtration system and pumps, most people go by without bothering with adding a sump to their FOWLR tanks.

How Long Does It Take To Cycle A FOWLR Tank?

A healthy tank environment is essential for any type of fish tank. And if you are establishing a FOWLR tank, you must be careful about what you pick and how you set things up. That being said, just because you are setting up such a tank does not mean you put everything all together.

You need to take time with your FOWLR tank setup and keep the fish for the last addition. Before that, you must ensure the tank environment is ready for having any living things inside it. And to ensure that, you must let your fish tank have a full cycle. And it can take a few to several weeks for the tank to cycle. But why is it necessary?

Well, when you add various components and elements into the fish tank, they do not immediately start working. To keep your tank environment clean and healthy, you will need good bacteria and algae growth. These will help balance the level or nitrite and other toxic elements on the check.

So once the good bacteria have overpowered the bad ones, your tank water will be safer to have fish. And only then you can add fish to the tank. Depending on your tank size and type, it can take 2-6 weeks for the cycle to be complete.

One of the easiest ways to know if the cycle has been completed is to watch out for the smell. Establishing new tank components will give away a smell that might bother you for some time. But once the smell begins to fade, the tank becomes ready to complete its cycle.

You can also test the water to find it out. If the test shows that the tank water has 0% ammonia and nitrite, your tank water is fish-safe. And making sure the tank is cycled before adding fish prevents unnecessary death in your tank.

What Temperature Should My FOWLR Tank Be?

The temperature of the ocean determines what kind of lives it will have. But in captivity, you must know what you will have in your tank and adjust the temperature accordingly. And in the case of a FOWLR tank, the ideal temperature falls somewhere between 75°F-80°F or 24°C-27°C.

But the precise temperature level should depend entirely on the type of fish you added to the tank. So you have to observe your fish and other added organisms to check if they are doing well in the given temperature.

But before you set up a heating system for your FOWLR tank, you must consider several things. Such as-

  • Does your tank have excessive growth of algae and other waste? If yes, setting up a higher temperature might not be a good idea.
  • The tank water must have good water movement and aeration. Otherwise, the water will automatically get warm. And with the increased temperature and additional warmth, the fish can easily suffocate and die.
  • Your environment is also vital for the tank’s temperature rise and fall. So you must pay attention to that as well.

How Much Flow Should A FOWLR Tank Have?

Having an excellent flow rate or turnover is essential for any fish or reef tank. As for the FOWLR tanks, the flow rate should neither be too high nor too low to maintain a healthy tank environment. But what should be the flow rate for such a tank?

For a FOWLR tank, the flow rate should be 10 to 20 times per hour. But the summed-up rate should depend on your tank’s size and its turnover time. Here is how you can find the ideal turnover rate for your FOWLR tank-

Tank size x turnover time = flow rate

It means if you have a 60-gallon tank, you should multiply it by 10 or 20. And the result is the recommended flow rate for your tank, which should be between 6000 gph (gallons per hour) to 12000 gph. However, it is best to stick to the maximum flow rate.

But I also encourage you to check to see if the tank fish seem comfortable enough with the flow rate. You can increase or decrease that depending on their condition.

Does Algae Mean My Tank Is Cycled?

Once you set up your FOWLR tank, minus the fishes, you will notice a gradual change in the tank environment. With all new substrates and organisms added, the tank will smell. And the fresh and clean-looking tank will appear less clean and clear.

The live rocks, plants, and substrates will have green algae growing on them. That is because the bacterial colonies begin to establish themselves in this new environment. And this is entirely natural for both the tank and the wild environment.

And as the algae begin to grow and take over the things in the tank, it means the cycling is nearly complete. It also means the tank is almost ready to have fish and other animals in it.

That’s right! You should never put any fish or animal without letting the newly set up tank finish its full cycle. Otherwise, the fish and animals will not be able to adapt well and may die because of various health and environmental issues.

Can You Have Too Much Live Rock In A Saltwater Aquarium?

One of the main features of a FOWLR tank is its live rocks. But as an aquarist or enthusiast, it is natural to get carried away and fill a big part of the tank with live rocks. Then you wonder if you overdid it. So, can you have “too much” live rock? Or, how much is too much?

Well, there is no specific answer to these questions actually. The amount of live rock you set up depends entirely on your choice and your tank size. But generally, professional aquarists suggest adding around 1 pound of live rock for each 1.5-2 gallons of water.

So you can tell that it is natural to add a good amount of live rocks to the tank. But you should also know that live rock can easily trap wastes, making it necessary to maintain the tank more often if you have a lot of them. That is why it is best to keep them slightly far from the tank glass so that you can clean them easily.

On the other hand, the live rocks should not block or limit your tank’s water flow, pump, filtration and swimming of the fish. If that happens, it is likely that you have set up too much live rocks.

Do Saltwater Fish Like High Flow?

There is always debate and confusion regarding whether or not saltwater fish like high water flow. And before knowing the answer, think of it this way-

The ocean is vast and wild. And there is no way for the flow to adjust, which goes on its own way. So saltwater fish are quite used to living and breeding in a high-flow environment. However, things in captivity can be different, and the flow rate depends on the tank’s size and what you have in it.

Nevertheless, it is better to have a high waterflow for saltwater tanks. Many people start with a low flow rate and increase it later. But that can be an issue with the fish’s adaptation skills. You can add multiple flow pumps and check if the fish are swimming around happily. If nothing seems out of place, your tank has the right flow.


Setting up a fish tank is not an easy job, especially when you are new to this. But most beginners prefer learning about a FOWLR tank setup because it helps you learn to set up other tanks comparatively effortlessly.

In a FOWLR tank, you not only keep fish but also live rocks. So you have to set up an environment that is suitable for all the inhabitants. And I believe this guide will help you achieve that easily.

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