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How to Set Up a Marine Tank

Posted by on Mar 25 2024

Setting up a marine tank can seem like a complicated process for beginners but with the right guidance, new fishkeepers can enjoy the beauty of a saltwater aquarium. Knowing about the different types of saltwater aquariums that exist and the kind of marine life that populates them helps to simplify saltwater tank setup and makes it less daunting. In this guide, we’ll delve into how to set up a marine tank successfully and the supplies you’ll need to get started.

Types of Saltwater Fish Tanks

When discussing aquariums, the terms ‘marine’ and ‘saltwater’ are often used interchangeably but they generally refer to a tank that is home to fish, invertebrates or plants that naturally live in saltwater. 

Before embarking into the world of marine aquariums, it helps to know that there are 3 main types of saltwater tanks. 

Fish-Only Marine Tank

For a budget-friendly marine setup focused on fish, consider a fish-only saltwater tank with minimal decorations like rocks or coral. With no live sand or rocks to help with filtration, be prepared for more maintenance, including frequent water testing and potentially longer cycling times.



A FOWLR aquarium (aka a fish-only with live rock tank) combines fish with live rock for natural biological filtration, introducing beneficial bacteria essential for breaking down harmful chemicals like ammonia and nitrites. This setup provides stability to water parameters, acts as a supplemental filter and can be considered a middle ground between a fish-only marine aquarium and a reef tank.


Reef Tank

Reef tanks are visually stunning but are the most challenging to maintain, often housing more coral and invertebrates than fish. Reef aquariums require additional lighting for coral photosynthesis and strict temperature control for invertebrates, making them more expensive due to the extra equipment needed for optimal water quality.


How do I Set up a Marine Fish Tank?

In some ways, marine tank setup is similar to setting up a new fish tank but there are some extra steps you’ll need to take to create a thriving saltwater aquarium.

Choose your aquarium and fish. 

The planning stage is the most important part of the marine aquarium setup. This is the point where you decide whether you want to have a fish-only saltwater aquarium, a FOWLR tank or a reef aquarium. The type of marine aquarium you choose to set up dictates the equipment and marine life you’ll need to buy. If you’re wondering, ‘Can any fish tank be used for marine?’, the answer is yes, you can use any type of aquarium for your marine setup. However, do bare in mind that it is better to use one that is 40 litres or bigger.

Prepare your aquarium. 

The preparation of your saltwater tank can be split into stages. 


  1. First, you’ll need to clean your new aquarium. Avoid using harsh cleaning products that can leave behind chemical residue. Instead use a soft, damp cloth to remove any dust.

  2. If you are using a used aquarium, you should check it for any leaks. Do this by filling the tank with a few inches of water, and then leaving it for around an hour. A good quality aquarium sealant or glue will fix any leaks you discover.

  3. Finally, choose a safe location for your aquarium, away from high-traffic areas and heat sources. It’s best to decide on the location of your tank before filling it, as your aquarium will be very heavy and tricky to move after it’s filled. When choosing a location for your marine tank, make sure the surface it’s placed on can bear the weight of the full tank and accompanying equipment.

Add the substrate 

Choose a high-quality substrate suitable for marine aquariums. Whether you choose gravel, aquarium sand or live sand will depend on the types of aquarium you set. Whatever substrate you decide to use, be sure to rinse it off before adding it to the tank. If you add gravel, add it slowly in layers to avoid scratching the tank.

Fill your aquarium. 

A marine tank cannot use basic tap water, it needs to be filled with water that has been through reverse osmosis. A marine reverse osmosis unit will prepare the water or you can buy water that has already been treated. Alternatively, you can use water treatments and supplements to remove the chlorine from the water. 


You also need to add a salt mix and monitor the salinity of the tank. Salt mix manufacturers will often provide guidance on the amounts needed for each type of marine aquarium. The type of fish you keep in your tank will also determine the salt levels as it is best to maintain salinity levels that are similar to the fish’s natural ocean environment. Many beginner marine fish keepers often neglect to monitor the salinity of the tank so invest in a hydrometer to keep an eye on salt levels.

Install the aquarium equipment 

Now is a good time to install your filter and the additional equipment needed to get your aquarium ready. Installing a high-quality filtration system is paramount when setting up a marine tank. Marine environments can be sensitive to water quality, so good filtration is essential. Healthy marine life also relies on stable water temperature so it might be necessary to add a heater to your tank. If you install a heater, place a thermometer on the opposite side of the tank to ensure you have correct readings. When the tank has been filled, UV sterilisers can be added to reduce algae formation while including an airstone for aeration will help your fish live a healthier life in your tank.

Add your aquarium decorations

Choose your fish tank decorations and wash them before arranging them in the tank. It’s a good idea to do this step before starting the cycling process because adding decorations to your tank can affect the water quality if added afterwards. 

Cycle the tank  

Before adding the fish, it’s important to know how to cycle a marine tank. Cycling a tank helps to build beneficial bacteria cultures that act as a biological filter. These bacteria colonies are necessary for breaking down ammonia and nitrite which are harmful to fish, and converting them into less toxic nitrate. Adding live rock or a biological enhancer will kick-start the cycling process which can take 6-8 weeks to complete.


During the process, you'll need to monitor ammonia and nitrite levels regularly using water quality test kits and perform partial water changes as needed to maintain safe water parameters. As the beneficial bacteria colonies develop, you'll notice a decrease in ammonia and nitrite levels and a rise in nitrate. When the levels of ammonia and nitrite have dropped to 0 ppm, it is safe to gradually introduce your fish.

Add your fish 

When you have chosen a species of fish, they will need to be acclimated before introducing them to your tank. Be sure to add fish slowly as adding too many in one go can run the risk of unbalancing the tank’s ecosystem which will be harmful to the fish. 


To acclimate your new fish to the aquarium water, start by floating the sealed bag on the water's surface for about 15 minutes. This helps the water inside the bag adjust to the aquarium's temperature. After 15 minutes, carefully open the bag while ensuring it stays floating. 


Gradually add half a cup of aquarium water to the bag every 4-5 minutes until the bag is nearly full. Then, remove half of the water from the bag (avoid pouring it into the aquarium). Continue adding half a cup of aquarium water to the bag every 4-5 minutes until the bag is full again. 

Finally, use a fish net to gently transfer the fish from the bag to the aquarium, and safely discard the bag and the water it contains. This method helps minimise stress on the fish during the transition to their new environment.


Supplies for Marine Tank Setup

Whether you need water testing kits, filters, filter media or a variety of fish tank decorations, CD Aquatics has what you need to set up your marine tank. For more information, browse our aquarium supplies or contact us to find out more.

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