Marine Aquarium for Beginners step by step

Hello Marine Reader, if you have come this far with questions like:

What is needed for a marine aquarium?
How to make a marine aquarium?
How much is it going to cost me?

You have come to the right place. Make yourself comfortable because I am going to solve all your doubts about how to set up a marine aquarium in this small guide focused on the marine fish tank for beginners.

Currently, the art of aquarism has managed to recreate and maintain different marine ecosystems within an urn in order to enjoy their beauty.

The therapeutic benefits of observing a marine fish tank, in addition to its beauty, make aquarium hobby an increasingly widespread hobby.

In fact, it is very common to find aquariums in places such as dentists’ offices or other places of stress.

Until not so long ago, a marine tank was complicated, and an invertebrate tank was only for experts. But today, thanks to technology, you no longer need to be an expert to enjoy your own saltwater aquarium.

You no longer have to be an expert to have your Marine Aquarium and enjoy its exotic beauty.

A marine fish aquarium is not only decorative and therapeutic, the saltwater aquarium offers other virtues such as being entertaining, instructive and creative. In addition, the simplest fish tanks do not require as much time or space when compared to other pets such as dogs and cats.

In short, aquarium hobby is the recreation of a natural underwater environment, and in this article we are going to discuss saltwater fish tanks for beginners that simulate a marine ecosystem: The Marine Tank Step by Step.

But what is a marine aquarium?

The marine fish tank is a transparent urn with the necessary mechanical devices that make it possible to simulate an underwater marine ecosystem.

If you are a beginner in the world of aquariums, marine fish tanks are not the most recommended option to start with.

Although technology has made maintaining a saltwater aquarium much easier, experts still recommend starting with freshwater aquariums. You can take a look at our beginner’s guide to freshwater planted fish tanks or our guide to the tropical aquarium.

Marine Waters

Generally speaking, most marine aquarium inhabitants come from coral reefs in tropical seas, where the temperature is very stable.

In particular, one of the main suppliers of marine aquarium fish is Australia’s Great Barrier Reef. Fish of incredible colors populate these crystalline waters.

Fish from the reefs of the Red Sea, the Caribbean or the Maldives are also highly valued.

In Atlantic waters there are species that do not support large variations in salinity or temperature, so they are not highly recommended for the aquarium of marine fish. However, in the Mediterranean there are endemic species suitable for aquarism.

In brackish areas, the level of salt in the water is lower, and since they are usually shallow, the climate strongly conditions them. For this reason they inhabit species that are very resistant to variations in salinity and temperature, but difficult to breed in captivity.

The marine aquarium step by step

Let’s see how to set up a marine aquarium step by step. This requires a bit more knowledge and technique than the freshwater aquarium, so marine tanks are comparatively a bit more difficult to maintain.

The most common questions asked by people who are interested in starting a marine aquarium is “how to start a marine aquarium?” . Then comes another similar question, «What do you need for a marine aquarium?» .

Here we are going to deal with these two questions and many more to show you that building a marine fish tank today is not that complicated. Our goal with this guide is for you to be successful in setting up your own saltwater aquarium.

First of all, before thinking about buying aquariums, we are going to differentiate the five main types of marine aquariums.

Types of marine aquariums

  1. 1. Fish-Only Saltwater Aquarium: This type of seawater aquarium offers only a variety of species of saltwater fish with bedrock (not live rock), no corals.
  2. 2. Fish Only With Live Rock: This type of marine fish tank known as FOWLR (Fish Only With Live Rock) offers only a variety of species of saltwater fish with live rock. Live rock is coral reef fragments naturally colonized with marine life, including invertebrates, sponges and millions of beneficial nitrifying bacteria that provide excellent supplemental filtration.
  3. 3. Coral Reef Aquarium: This setting replicates a beautiful ocean reef environment with hard corals, soft corals, invertebrates, and various species of fish.
  4. 4. Nano tank: Generally 100 liters or less, the reef ecosystem is the most difficult and only recommended for the most advanced aquarists. Small marine coral tanks need a high level of care to avoid stress to the fish or corals. However, a 10-20 gallon fish-only saltwater tank with two Clownfish can be relatively easy.
  5. 5. Specific marine tank: This saltwater environment focuses on a specific species, such as seahorses, sharks, rays, jellyfish, etc.

Main parameters of water in marine aquariums

Keeping your seawater aquarium parameters within the proper range is crucial to the overall health and well-being of your fish, corals, and invertebrates.

Most saltwater inhabitants cannot tolerate even small fluctuations in aquarium water parameters.

The key to starting and maintaining a saltwater aquarium is stability.

In a generic way, here are the main parameters of a saltwater aquarium:

  • The sea is a very stable environment, and in tropical seas the temperature ranges between 24 and 28 o C, while in cold water it is between 16-18 o C. Generally, marine fish are more sensitive to any change in the conditions in which they live. their habitat.
  • Marine fish and invertebrates need a pH that fluctuates between 7.8 and 8.4.
  • Salinity ranges from 1018-1028 for fish, with 1023-1025 being the most optimal range. For invertebrates the salinity cannot oscillate beyond the 1023-1025 range.
  • The presence of ammonia, nitrates and nitrites in the marine environment is null, so many fish have a minimal tolerance to these compounds. For many of them, it is necessary to maintain a level below 5 milligrams / liter (ppm) in saltwater fish tanks.
  • The alkalinity of the water must also be controlled, which must range between 2.5 and 3.5 mEq/l.
  • A marine fish tank with invertebrates and reefs needs extra Calcium and other trace elements so that they form their skeleton. The calcium level should move between 400-450 ppm of Ca++.
  • The oxygen concentration in the water should never be less than 7 mg/l.

It is likely that some of these parameters sound «Chinese» to you. But the objective of this guide is that when you finish reading it you understand what these parameters refer to, and you have the basic notions to know how to set up a marine aquarium.

Now we are going to see the marine aquarium accessories necessary to build a saltwater fish tank.

Seawater aquarium: the necessary equipment

First of all, marine aquariums need more and better technical means than freshwater aquariums.

The specific characteristics of the necessary technical accessories, as always in the aquarium hobby, will depend largely on the aquatic species you choose for your fish tank.

But what is needed for a marine aquarium?

For those who are wondering how to start a marine aquarium, they should know that the first thing is to get the necessary aquarium accessories to start a marine aquarium. Generally, these are the main accessories that any saltwater fish tank requires:

  1. The aquarium itself, that is, the container, the tank and its base or furniture.
  2. Filtration and oxygenation system.
  3. sump
  4. Skimmer or skimmer.
  5. UV sterilizer.
  6. High quality lighting.
  7. Temperature control and adjustment.
  8. Sea salt
  9. Substratum
  10. live rock
  11. test kits

The Aquarium

The location and size of the marine fish tank is the first thing you have to decide on.

The characteristics of the urn end up conditioning the other aquarium accessories and components, and also the species that will occupy it.

On the button below the image you can see a sample of different fish tanks in the Amazon storefront.

You already know that the bigger the marine tanks are, the easier it is to keep them stable. Or what is the same, the smaller, the more complicated.

By the way, there are the Complete Marine Aquarium Kits with the saltwater fish tank, the built-in filtering and the necessary marine aquarium equipment.

Complete marine aquarium kit

It is an option to start, ideal for those who want to buy a marine aquarium NOW, quickly and easily. Below you can see some examples of Amazon ‘s complete marine aquarium kit.

Tank Dimensions

It’s very simple, the filter for example, a 200 liter tank needs a filter with more capacity than a 100 liter one.

In the market offer you can find from a 13-liter marine nano aquarium to gigantic marine fish tanks.

  • The height of the marine aquarium I recommend that it be moderate,around 60cm. This will make maintenance easier and you will not have problems with lighting.
  • I recommend that the width of the marine fish tank bebetween 35-50 cm.
  • The length is conditioned by the physical place and the budget.

The saltwater aquarium for a beginner aquarium hobby should not be less than 80 liters.

You must bear in mind that the smaller a marine fish tank is, the more difficult it is to keep under control. And on the contrary, the older it is, the more stable its conditions are and the smoother its changes.

How to know the liters of saltwater fish tanks?

To know the liters or the capacity of an aquarium, use this simple formula:

Height x Width x Length (cm) / 1,000 = X Liters

For example, if we have an urn 60 cm high x 50 cm wide x 80 cm long:

60 x 50 x 80 / 1,000 = 240 liters

Nano marine aquarium

If what you want is a small marine aquarium or marine nano aquarium, you can choose one of the following models.

But keep in mind that the smaller the marine tank, the more difficult it is to keep the parameters stable. Any minor alteration of the basic levels can kill the inhabitants of your small saltwater fish tank. For this reason, a marine nano aquarium is often recommended for experienced aquarists.

Where do I put the marine aquarium?

The first thing you have to decide is where you are going to place your marine aquarium for beginners, and for this, keep these three factors in mind:

  1. 1. Avoid direct light from windows:because it will upset the temperature and cause an increase of algae in your marine fish tank.
  2. two. Avoid sudden changes in temperature:Be careful around heating and air conditioning or any other devices, as sudden changes in temperature are very detrimental in beginner saltwater tanks.
  3. 3. Accessibility for maintenance:Don’t forget that the marine fish tank requires regular maintenance so easy access is necessary.
  4. Four. Electrical outlet:A grounded plug is necessary for the electrical devices of the marine aquarium equipment such as the light, the filter, the air conditioner…

The place where to place the aquarium is the 1st step, which will affect you for the 2nd, deciding the size of the tank.

Filter for marine aquarium

In any tank, you have to use a filter to purify the water and thus prevent it from becoming toxic to the inhabiting species.

The biological cycle generates waste such as excrement and organic remains in general. These wastes need to be processed so that they do not accumulate and turn the aquarium into a toxic environment.

This is where the figure of aquarium filters appears. The saltwater filter cleans the medium from impurities using different media, and also keeps the parameters of the marine fish tank stable.

The biological cycle of the marine tank, which is very similar to that of fresh water, but requires more control. This is due to the low tolerance of saltwater fish to ammonia and nitrates.

For this reason, the marine aquarium filter is very important for the health of the inhabitants of saltwater aquariums.

The low tolerance of marine fish to these compounds makes the filtering of water in marine fish tanks a vitally important process.

The salt water filter is based on the Nitrogen Cycle, and uses the purification of bacteria, in addition to physical and/or chemical cleaning.

Keep in mind that many marine aquarium fish will not withstand levels higher than 5 milligrams/liter (ppm).

Filtration classes in the marine aquarium

Let’s quickly see the three types of water filtration used in a beginner marine aquarium:

  • Mechanical Filtration:
    Very fine materials are used to remove solid particles of dirt. For example, sponge or perlon.
  • Chemical Filtration:
    This filtering is used to absorb impurities or perform chemical changes in the water (pH, hardness, etc.). It also has a specific use, such as Activated Carbon to remove drug residues.
  • Biological Filtration:
    This filtering is done by friendly bacteria transforming toxic elements into nitrates.

The key is biological filtration, and in beginner saltwater tanks the importance of filter aging or cycling is vital.

Maturation of the filter for salt water

In addition, in this settling process the most important thing is the maturation of the filter. It is the time that bacteria need to colonize the marine fish tank and almost immediately transform ammonia, ammonium and nitrites into nitrates.

This period is also called marine aquarium cycling, and naturally it usually takes a few weeks for the nitrifying bacteria strain to settle in the tank. If you want to know about aquarium cycling, just follow the link above to get to our article on tank maturation.

This aquarium maturation ends when ammonia and nitrite levels are at zero. Then you can put the first fish in the marine tanks.

The maturation of the filter is essential to have a healthy environment for your fish.

It usually requiresabout 4 weeksthe colonization of nitrifying bacteria in the filter in a natural way.

But there are also items for sale that shorten this process, favoring the settlement of bacteria and eliminating harmful substances. Here you can see a sample of this type of products.

Marine aquarium filter maintenance

Cleaning the filter materials is very easy, but there is a very important factor:

If you use normal water, from the tap, to clean the filter you will load all the friendly bacterial colony because the mains water comes with chlorine.

ALWAYS use the water from the marine aquarium itself to clean the filter materials.

And how often do I have to clean it?

That depends on each marine fish tank, but when you notice that the flow decreases, it will indicate that it is time to clean.

Do not forget that the material where the bacteria are found, you should not do a deep cleaning, because you will be left without a biological filter.

Finally, the rest of the filter material should be washed well.

Marine aquarium filter classes

Today we have a wide range of filters to choose from, and the first thing you should take into account is its capacity, so that it purifies the aquarium of marine fish a minimum of 3 times an hour.

So if you have a 60 liter urn, you need a filter that cleans 180 liters per hour.

Keep in mind that the more powerful your marine aquarium filter, the better the health of your aquarium.

First, we are going to see the filters common to any type or class of tank, marine or not.

Filter for indoor marine aquarium

The effectiveness of the internal filter is usually a bit limited, although it is very useful in small marine aquariums. In addition, they can also be used as support filters in larger saltwater fish tanks.

These devices are usually very simple to use and also inexpensive. By clicking on the button you can access Amazon to see some examples of internal aquarium filters that are on the market.

The bad thing about the internal marine aquarium filter is that it reduces the volume of the marine fish tank and they are not very aesthetic.

The most common is that you only use a sponge that acts as a mechanical and biological filter. There are also some models with a place to insert biological medium.

Backpack marine aquarium filter

Compared with the internal marine aquarium filter, the waterfall filter has a more efficient filtering and provides greater oxygenation of the water. They do not reduce the volume of the marine fish aquarium when placed outside, but it is still visible.

Two designs are common, one with a cartridge and the other with a place to place the filter loads. To see an example of a waterfall filter on Amazon you can click on the button under the image.

As they usually have more room to place filter loads, it is more versatile. In addition, they usually have a biological load apart from the sponge.

In this type of filters, maintenance is easier because it is usually more accessible, and it affects the aquarium inhabitants less.

Filter for external marine aquarium

The drawback of these filter canisters is that they require additional space, in addition to their price, of course.

The good thing is that they are completely external to the marine tank and can be easily hidden. They also have the highest capacity for filter media, making them the most efficient filters for saltwater fish tanks.

To collect dirty water from the tank, the external filter uses a hose. It then forces the water to pass through the filter media, ensuring maximum contact time. Finally, the clean water is returned to the urn through another hose. The button below the image shows you various examples of external filters in the Amazon storefront.

Now we are going to see these other filter systems mainly used in marine aquariums: marine aquarium filters

Protein Skimmer for marine aquarium

The operation of the protein skimmer is based on the production of small bubbles that drag the proteins present in the water before they are transformed into toxic nitrogenous compounds.

These bubbles accumulate on the surface in the form of foam that falls into the waste glass, eliminating the proteins in the water.

Therefore, it can be said that a skimmer helps prevent the formation of ammonia and nitrites in marine fish tanks. You can see some example of protein skimmer on Amazon if you click on the button under the image.

Place water pumps in the right places to create currents in the marine fish tank, it will improve the effectiveness of the skimmer.

This device also oxygenates the environment and improves the Redox potential, which is the ratio between additions and losses of oxygen in the chemical processes of the aquarium.

Oxygen demand in a tank is constant, so improving Redox potential is always important.


The Sump or Sink is an additional tank connected to the main marine aquarium, whose purpose is to house the different systems that make up the equipment such as filtering, air conditioning, skimmer, etc.

This extra tank consists of several compartments and there are thousands of designs and configurations. By clicking on the button under the image you can see different offers of sump for marine aquarium on Amazon.

The installation of the Sump in your marine aquarium will provide the following benefits:

  1. Larger volume of water.
  2. It facilitates the superficial cleaning of the water.
  3. Constant water level.
  4. Facilitates and improves regular maintenance.
  5. Improves oxygenation and water circulation.
  6. Greater pH stability.
  7. Helps the growth of macro-algae.
  8. Hide all equipment.
Dry – Wet Filter

The wet-dry filter is used in the large-size marine fish tank. This type of filter system is not very widespread, but it is highly effective.

The key to this marine aquarium filtration system is to house a medium rich in oxygen that facilitates the settlement of a large colony of friendly bacteria. The wet-dry filter is one of the most effective biological filters.

If you click on the button below the image you will see several models of the Wet Dry filter type sold on Amazon.

In this type of filter, the bacteria do not absorb oxygen from the water, but from the air. To achieve effective gas exchange these filters have a large contact surface as well as open areas.

Bioballs are usually the biological filter of these filters for marine aquariums. These hollow balls also known as bio balls are designed to facilitate the growth of the bacteria colony.

Because these filters need more supervision and maintenance, it is not highly recommended for the beginner marine aquarium.

In addition to purification, filtering has another mission of great importance, which is to generate currents in the water.

For this, place the water inlet of the filter on the opposite side to the outlet.

Lastly, DON’T forget theregular water changes and cleaning of mechanical filters with salt water from the tank itself, which are essential to maintain a healthy marine fish aquarium.

Saltwater fish tank oxygenation

The oxygen concentration in saltwater fish tanks always tends to decrease. The two natural ways of providing oxygen are not enough:

  1. 1. The oxygen of plants when carrying out photosynthesis.
  2. 2. The gas exchange that occurs at the surface of the water.

If you see your fish gasping at the surface, and making very rapid gill movements,lack of oxygen.

A mistake that is repeated a lot is to suffocate the fish due to having an excess population.

If you are interested in knowing more about what plants can contribute to an aquarium, you can go through our Guide to the Planted Aquarium for Beginners.

Traditionally, aerators have been used to alleviate the lack of oxygen.

An aerator is an air pump with one or more diffusers, which emits the typical stream of bubbles.

Many mistakenly believe that these bubbles are the ones that oxygenate the environment. But it is actually the movement on the surface of the water that oxygenates the tank.

The new filtering systems are replacing the classic aerators in marine fish tanks because they are much more efficient in their task.

Aeration also avoids hot and cold areas, favoring a stable temperature throughout the aquarium.

You can browse this type of oxygenating devices for the marine fish tank on Amazon if you click on the button below the image.

Oxygen Relationship – Temperature

The temperature of the medium greatly influences the oxygen concentration. The higher the temperature, the less oxygen we will find in the water of the marine aquarium.

Relationship between water temperature and oxygen

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