Beginners Guide To Setting Up A Saltwater Aquarium

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In this article, I’ll walk you through the basics of saltwater fish tanks, as well as a step by step guide on how to set up a saltwater fish tank.

Keep reading to learn how to create your very own saltwater aquarium.

Equipment You’ll Need

The first step in assembling a saltwater aquarium is to have a general idea of what equipment you’ll need.

Here’s the equipment you MUST HAVE.

Aquarium/Tank: Choosing the right tank is one of the most important decisions you’ll make. Be sure to pick an aquarium that can hold the fish you plan to stock. You’ll learn how to do this later in the article.

Lighting: Choosing a good lighting system can vary depending on many factors such as your tank size and fish you want to keep. Make sure the lighting you do choose can provide a good amount of coverage inside the entire tank.

Filter: Depending on the type of saltwater tank you want to set up, your filtration system can vary. One thing for certain is that you MUST have good filtration so don’t slack on it.

Powerhead: Having good circulation in your tank is important. Depending on the size of your aquarium, you can use one or more powerheads to provide good water circulation throughout the system.

Substrate: Here you need to decide on what type of material you want on the bottom of the tank. For beginners, I highly recommend you go with live sand!

Sea Salt Mix & Hydrometer: Sea salts are what make a saltwater or marine aquarium. You also need to test the salinity(saltiness) of your water using a Hydrometer.

Heater & Thermometer: Keeping a stable temperature inside your aquarium is crucial. For smaller aquariums(40 gallons or less), one heater works well to keep stable temperatures. For larger tanks, the use of multiple heating units is advised. To measure the temperature inside your aquarium, be sure to purchase an Aquarium Thermometer.

Water Test Kits: Testing your water is important. Be sure to look for aquarium water test kits that test for Ammonia, Nitrites, and Nitrates.

Maintenance Tools & Supplies: This category includes everything you need to clean a fish tank. Maintenance supplies you need include plastic buckets, tank cleaning tools such as a siphon tube/hose, algae scrapers, and nets.

Types Of Saltwater Tanks

There are a lot of things you can do with a saltwater tank. Here are the main types of marine aquariums.

Fish Only

Let’s be honest with ourselves, the main reason we want to start an aquarium is to keep beautiful fish. If they are all you want, why bother with anything else?

Fish only tanks are the most basic and cheapest type of tanks. The only requirements you’ll need to consider are those for your fish and not of other animals such as corals.

There are two types of fish only tanks, species and community tanks.

Although the most basic option, these tanks aren’t the easiest to set up. The reason is because you wont cycle your fish tank with live rocks. Without live rocks, you’ll have to manually introduce beneficial bacteria into your tank which can take some time.

Also, you’ll need to clean your aquarium more often. This means performing more water changes to maintain a high water quality.

Fish Only With Live Rock (FOWLR)

These tanks are the same as fish only tanks, just with live rock.

As previously mentioned, live rocks are helpful when setting up your tank. Not only do they help with the setup, they also clean your tank, which saves you time!

The reason why live rocks are so useful is because they have bacteria populations that decompose ammonia(toxic) and nitrites(toxic) into nitrate(not toxic).

The only downside to using live rocks is their price. Typically 1lb of live rock can cost anywhere from $5-$10. This really isn’t expensive in the grand scheme of things, considering the initial cost of the equipment for your saltwater aquarium.

For FOWLR aquariums, you’ll also need to change the lighting for any photosynthetic organisms growing in the rocks.

Reef Tanks

Coral reefs are without a doubt the most attractive ecosystems in our ocean, possibly even our entire planet. For that reason, many try to capture its beauty in their home aquariums.

The main difference between reef tanks and FOWLR tanks is that you’re keeping live corals. For beginners, this can be a challenge because corals require unique water qualities and lighting. These can be difficult to monitor regularly. 

Reef tanks are also expensive too! You will need to purchase specific equipment for reefs and the cost of corals can also add to the total price as well.

Setting Up The Saltwater Tank

Now it’s time to assemble your saltwater tank!

Setting up a saltwater tank is similar to setting up a freshwater one, just with a couple extra steps. If you’ve set up a fish tank before, this should be a walk in the park.

Step 1: Planning Your Tank

Planning your tank is the first and most important step in setting up a tank smoothly. Be sure to plan all of your equipment around the fish and corals you want inside your tank.

For example, do you want to keep larger fish? In that case, you’ll want to purchase a larger aquarium with stronger filters. 

Think about all of your fish’s requirements and your aquarium will start taking shape!

Step 2: Preparing Your Tank

Once you have an idea of what you need, you can start buying the equipment and get everything ready. The first thing we’ll need to do is clean the tank.

There’s no exception to giving the tank a thorough cleaning. Even new tanks need cleaning to get rid of potential chemicals and dust.

When cleaning, NEVER use soap or household cleaning products as these can give off harmful chemicals to your aquarium. Instead, using a wet cloth to wipe away any dust or particles will get the job done safely! 

Cleaning a used tank is a bit more difficult. You’ll want to remove any debris inside the tank and clean the inside and outside using vinegar.

Also, if you own an acrylic tank, be more gentle in your cleaning as they tend to scratch easily. To minimize the risk of scratching, use a cloth.

After you’re done cleaning, you’ll need to check for leaks. Add a couple inches of water and leave it for an hour. Then, check for any signs of leaking. To fix a leak, use aquarium sealant.

Step 3: Finding the Right Position

After you’ve cleaned the tank and checked for any leaks, it’s time to find a good position for the tank.

Wherever you decide to put your tank, make sure it’s not directly exposed to sunlight. Exposing your tank to direct sunlight will kickstart an algae bloom inside your tank which is a sight no fishkeeper wants to see.

Also, make sure that the tank is near a direct power source.

Keep in mind that a 50 gallon tank can weigh nearly 600 pounds once filled, so make sure your floor will be able to support the weight. Finally, pick a position you’re happy with because after you’ve filled your tank, it’s going to be near impossible to move. 

Step 4: Adding the Substrate

The time has come to start filling your tank, starting with the substrate. The type of substrate you choose is all up to you, however we recommend live sand for beginners. 

Most people aim to put 1-2 inches of substrate in the bottom of their tanks. To do this, you’ll need to add 1lb of substrate per gallon of water to get a 1 inch thick bed of substrate. For a 2 inch bed, you’ll need to add 2lbs of substrate per gallon of water. 

Below is a table for finding how much substrate your tank needs:

Tank SizeAmount of substrate needed
30 Gallons30-60 LBS
45 Gallons45-90 LBS
55 Gallons55-110 LBS
75 Gallons75-150 LBS
100 Gallons100-200 LBS
120 Gallons120-240 LBS

When you purchase substrate, it comes covered in dust particles. For this reason you’ll need to clean it before you add it to your aquarium to keep the water clear.

Cleaning Substrate

To clean the substrate, put small amounts into a bucket and run water through it. Mix everything with your hand until the water cleans out.

After you’re done cleaning it, gently make a thin layer at the bottom of your tank so you don’t scratch the tank. Then pour the rest in. You can start designing the substrate. You may want a constant level or perhaps you would prefer some raised areas. No matter what you choose to do, be sure to do it here.

Step 5: Adding the Water

The next job is to add the water. But this step will require a little preparation.

First, make sure your water has been through reverse-osmosis(RO). You can buy water already in this condition, or you can opt in to use treatments.

You will also need to mix the RO water with sea salts. You can buy sea salts online or at your local pet store. The instructions on the package should tell you how much to use.

Finally, you’ll need to add some dechlorinator and your water should be ready to add!

When adding water, place a dish on the substrate to pour the water onto. This will prevent your substrate from being disturbed.

Step 6: Installing the Equipment

Nearly all aquariums require a filter, and most will need a heater. Some people also might need some additional equipment such as UV sterilizers, lights, protein skimmers, air stones, and automatic feeders.

In this step, all the equipment you purchased needs to be added into your aquarium. Most equipment is easy to install but filters can sometimes be confusing. There are many different filters out there from canister filters to gravel filters. All the installations are different and the manufacturer you choose should have a YouTube video to walk you through the installation. 

Position your heater on one side of the tank and position the thermometer on the opposite side. This will ensure you are keeping consistent temperatures throughout the tank.

Step 7: Adding the Decorations

Now it’s time to get creative! This is where the image of the tank in your head turns into reality.

Adding plants and decorations is one of the best parts of setting up the tank!

The preferences for decorating your tank is all up to you. Some people like a natural design while others enjoy theming their tank.

Rinse any item before you place it into your tank. This will help remove dust and maintain clear waters.

Step 8: Cycling the Tank

By now your tank is all set up, but it’s still not safe for fish yet. You must cycle your fish tank.

The goal here is to build up bacteria to act as biological filtration. One type of bacteria will convert ammonia to nitrites. Another will convert nitrites to nitrates. The reason this is important is because ammonia and nitrites are toxic to your fish. Nitrates are also toxic to your fish in large quantities which is the reason you need to perform regular water changes.

To gather these beneficial bacteria, many use live rocks. These rocks already developed the bacteria to add to your tank.

Choose light rocks as they have lots of interior gaps, which means they have a greater surface area for bacterial growth.

For those with Fish Only tanks, or if live rocks aren’t working, you can add ammonia to kick off the cycle.

Regularly test the water in the tank. As you do so, you should notice a spike in ammonia, followed by a spike in nitrites. Once both of these chemicals reach 0ppm(parts per million) the cycle is finished. 

The process should take about 6-8 weeks. Cycling your tank is a bit more complex than this, so we go more in depth in our beginners guide on how to cycle a fish tank.

Step 9: Adding Fish!

Now that you have a safe, cycled aquarium, it’s time to add your fish! 

When adding fish, be sure to not add too many at once, as this will overthrow your tank with toxic chemicals. Instead, slowly add them over a few weeks or even months.

Before adding anything to your tank, you’ll need to know how many fish per gallon your tank can hold. 

Fish are also sensitive to changes in water condition, so you’ll need to gradually acclimate them to the water in your tank.

Here are a few steps to acclimating fish:

  • Turn off all aquarium lights.
  • Float the bag on the surface for 15 minutes.
  • Cut open the bag and roll down the top.
  • Add half a cup of water to the bag every 4-5 minutes until the bag is full.
  • Pour out half of the bag’s water.
  • Add half a cup of water back into the bag every 4-5 minutes until the bag is full again.
  • Transfer the fish to the tank with a net

After adding the fish, continually monitor them over the next 24 hours to check that they are healthy. Some things you can look for is that they are eating during feeding times and their moving habits.

Stocking Your Tank With The Right Fish

Saltwater fish come in many different shapes and sizes and have their benefits and cons. Choosing the right fish for your tank is vital for the future of your saltwater ecosystem.

For beginners, choosing a small, hardy fish that isn’t aggressive is a good idea.

One of the best saltwater fish for beginners is the clownfish. Popularized by the movie Finding Nemo, these hardy species of saltwater fish are a good option for beginners. These fish are beautiful, playful, and add excitement to any aquarium!

If you haven’t made up your mind yet, check out our guide on the 21 Absolute Best Saltwater Fish for Beginners. All the fish on the list have hardy natures, and bring a stunning look to your aquarium.

Common Questions About Starting a Saltwater Aquarium

When starting a saltwater aquarium, you’ll have many questions to ask yourself. Here are some answers to common beginner questions.

How Much Does It Cost To Get Started? 

The cost of starting a beginner saltwater fish tank will typically be anywhere from $1000-$3000 depending on your equipment.

Saltwater fishkeeping isn’t a cheap hobby, but is differently a rewarding one. After setting up your tank, the costs aren’t extremely unbearable. Usually, your biggest expense is going to be your fish, which usually costs anywhere from $50-$100 depending on the breed.

What Size Tank Should I Get?

Beginners should have tanks no smaller than 40 gallons. The reason for this is because of how difficult it is to maintain stable water in smaller aquariums. 

Generally, the bigger your tank is, the more flexible maintenance will be. For instance a 5 gallon tank needs attention every day. 20-gallon tanks need attention every couple of days. A 40-gallon tank should be maintained weekly. Finally, a 125 gallon tank needs water changes every 2 weeks.

For beginners, I recommend going with a 55 gallon tank, as I’ve found this as the sweet spot for many saltwater fish.

Can I Transform My Old Tank Into A Saltwater Tank?

The answer: Absolutely!

In fact, many saltwater aquarists(including myself) use old tanks for saltwater fish tank setups. As long as you have the basic equipment to keep a thriving saltwater aquarium, you’ll be just fine borrowing a used tank.

Before keeping any fish inside the tank though, be sure to clean it with vinegar and remove any decorations.

The only equipment I recommend you get new is a filter. The reason for this is because your old tank filter contains many different bacteria cultures, which can overwhelm the water quality.

As long as you let the tank cycle and maintain regular cleaning schedules, you’ll be just fine using an old tank!


Starting a saltwater aquarium requires a lot of thought. The most important step is planning. 

Knowing what to plan for is vital in the success of your saltwater aquarium. Think about which fish you want to keep, then decide on things like aquarium size, equipment, and decorations. 

Don’t know which saltwater fish you want? Check out our list of the 21 Absolute Best Saltwater Fish For Beginners.

Photo of author
Hey there, my name is Gunnar Kennedy. I'm a fishkeeping enthusiast who's been in the hobby for over a decade now! I love sharing new ideas and helping others care for their aquatic friends!

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