Starting a Saltwater Aquarium

The first question that comes to mind when starting up a saltwater aquarium is how much maintenance is needed. The challenge to this question is that the maintenance required varies with every aquarium, depending on a number of different factors. When deciding to keep a marine aquarium, it’s important to do a lot of research (which this guide aims to assist you with). The more you know, the more you’ll save from doing it right the first time, and being able to keep your aquarium alive and healthy.

 Aquariums come in many different sizes and can be suited for many different purposes, each demanding a different level of care. There are most certainly Saltwater tank options that require infrequent water changes and low maintenance. No matter what type of tank you keep, there are certain responsibilities to maintain a saltwater tank.

 We offer free in-store water tests because you will need to maintain proper water parameters (including pH, salinity, nitrates, ammonia, and temperature). The frequency of water changes that will be needed depends on your filtration set-up. Adding filtration devices, such as a protein skimmer, refugium, and/or sump to your aquarium, will help keep your water quality stable. With the use of such filtration devices, I recommend a water change once every 2 to 4 weeks. It’s important to mention, however, that some tanks may be fine with no water change for months (so long as water supplements are added and fresh water top offs are given regularly). It is important to know that when evaporation occurs, the salt stays in the water; therefore, to top off you always use fresh R.O.D.I. water.

 The type (and size) of your Saltwater aquarium will help determine the amount of maintenance needed. Some people are surprised to learn that sometimes larger tanks require less maintenance because the protein skimmer helps filter and clean the water for you. If you are keeping a Fish Only tank (aka FOWLR) it requires less water changes than a tank with Coral.

 One of the most fascinating features of a saltwater aquarium is the productivity of each living thing in the dynamic ecosystem. Invertebrates—such as snails, crabs, and shrimp—each benefit the aquarium by eating the algae and other waste in the tank. Certain types of fish can also contribute to the overall well being of your reef community—for instance, some will eat Ich (a type of parasite that makes some fish sick). Planning your aquarium carefully will help guarantee that you set up a productive and peaceful reef community, with a level of maintenance that you desire.

 I. Types of Saltwater Aquariums:

Reef Tank- An aquatic community of reef safe tropical fish, corals, and invertebrates (i.e. crabs, snails, shrimp, starfish, anemones, etc.).

 A Saltwater reef aquarium is a mini-ecosystem gleaming with dynamic life and exquisite colors. Each organism in the reef community contributes productively to the overall well being of the reef. A myriad of different types of tropical fish, coral, and invertebrates (inverts) provide reefkeepers an opportunity for a unique and thriving ecosystem, as well as a living piece of art.

 The biggest difference between a Reef tank and any other saltwater tank is the lighting. Corals need light to photosynthesize and stay healthy. Reef tanks thrive with enhanced water filtration and water conditioning (ranging from every couple days to weekly). Adding a sump below your aquarium creates a more stable tank by increasing the water volume, and provides a nice way to also keep a protein skimmer or refugium hidden under or behind your tank-system. Reef tanks can range in size from a small desk tank to a massive aquarium, whichever you desire.


FOWLR- (Fish Only With Live Rock) Keeping a tank without Corals requires less responsibility, as Corals require cleaner water quality (better filtration) and stronger lighting. There are options available to use fake corals if you still want to add some color and texture to your tank.

 **Live Rock provides endless benefits to a Marine aquarium because it supplies the denitrifying bacteria that a closed system aquarium depends on to maintain life. Without live rock, when a fish poops it would poison itself.

Predator Tank- Because there’s an endless variety of tropical fish, it’s important to learn the characteristics of each before building your reef community. While many fish that can be kept in a FOWLR tank can coexist with Coral and other fish, there are others (such as many Angelfish) that will eat Coral or fight with other fish to death. A predator tank, when planned properly, can consist of larger fish that live with other large fish (such as Grouper, Lionfish, Eels, and most Triggerfish) that would otherwise eat smaller fish.

II. Types of Equipment

There are many types of equipment available to help make fishkeeping easier, some more essential than others. The essential equipment and materials to start a saltwater aquarium include:

  • Tank: A Biocube is a 29 gallon tank that comes with the whole package, including the tank, light, and filter. An advantage to getting a biocube is that the light it comes with is high quality enough to keep Corals.
  • Light
  • Filter
  • Heater
  • Thermometer
  • Hydrometer or refractometer: measures the salinity and specific gravity
  • Powerheads (which create movement and circulation that simulate the ocean currents and tides). You can use other types of equipment instead, but saltwater aquariums need some sort of flow and movement in the water.
  • Substrate (i.e. Sand or Gravel)
  • Live Rock
  • Water conditioners/supplements: talk to us in store about which types will work best for you.
  • Food (frozen and/or pellets, seaweed, etc): All fish appreciate varied diet (i.e. meat, herbivore)
  • Salt
  • 5 gallon Buckets for water changes
  • Algae scraper or magnet buddy help to  keep your aquarium clean

   i. Some of the most beneficial devices you can add to your tank include a:

                     ▪  Protein Skimmer    ▪  Refugium     ▪ Sump    

 What is a Protein Skimmer? When you’re walking along the ocean and foam washes ashore, this is the organic waste produced from marine organisms. In an aquarium, the protein skimmer produces thousands of macrobubbles that attach to this type of waste and proteins, which is then disposed into the skimmer. Protein skmmers cannot be kept on a freshwater aquarium, but this is the best piece of equipment for Marine tanks to alleviate water changes for the owner.

 What is a Refugium?  

An area separate from your tank that allows vulnerable species to thrive—such a copepods, amphipods, and various macro algae-- which helps keep a clean water quality. Copepods and Amphipods are a great detrivore for your tank (they consume leftover food and waste, which creates undesired nitrates in the water if not removed). Tropical Fish also love eating Copepods and Amphipods. A Refugium can hang in the back of your aquarium, or even better in a sump underneath. 

Why use sump

A sump is a water system connected to your aquarium, either beneath or beside. It adds water volume to your overall system which creates a stable environment and optimal water quality. It also allows you to recreate the most ideal environment for your fish and corals. Sumps are aesthetically pleasing since all the external equipment (i.e. filtration devices, heater, etc) can be hidden in the sump. By adding a refugium to the sump you can mimic the nutrients and life available in a coastal lagoon. A sump is the most beneficial piece of equipment to add to your aquarium for the best water quality.

 Other types of equipment that will greatly enhance the quality of your tank, and make your job easier, include:

      ▪ Auto Top-off: Is essentially a float level, so when your tank water evaporates it automatically supplies a water topoff, which keeps a very stable salinity. It’s very easy to do your own water topoffs, however, it makes it more difficult to keep the ideal salinity level.

      ▪ Reactors (i.e. Calcium, Phosphate, Bio, Carbon): A piece of equipment that contains a specified media to maintain proper levels of nutrients in the water. For instance, a Phosphate reactor runs on G.F.O ( Grandular ferric oxide) that absorbs phosphates that can create algae and stress corals and fish.

III. Maintaining Water Parameters: Maintaining proper water parameters is a necessity for optimal health and longevity of the livestock in your tank. Water supplements and conditioners are available to ensure the proper and ideal water parameters. Depending on the intensity that you wish to dive into the hobby, you can build an aquarium that needs as little or much supplements necessary to thrive. While we offer free in-store water tests, there are also numerous types of test kit available so you can check your own water quality. Click here to see a detailed chart and description about keeping healthy water parameters.

                   TANK SET-UP

IV. Filling your Aquarium with Water    

1.       Lay your substrates: Substrates range from coarse to fine, and come in different colors. What you decide to use depends on what you and the type of fish you keep prefer.

2.       Fill with Salt Water and place live rock (it’s best to build caves with live rock)

*Live rock allows denitrifying bacteria to form (a natural biological filter) as the water settles.    

*Adding Microbacter (a water supplement) speeds up the denitrifying process, improves your biological filtration and rapidly improves your water quality and can help you decrease the time needed for this cycling period (which allows you to add fish sooner to the tank).

3.       Let sit for at least 3 days with filter and/or sump running

4.       Check ammonia, nitrates and salinity (or a full water test depending on the type of rock purchased). It’s possible that your tank will need to go through these phases for weeks before settling to accurate water parameters to sustain fish and coral.During this period the poisonous waste is being converted into a nontoxic substance that benefits your aquarium—you will know when you’re water gets to this ideal condition after numerous water changes and accurate water tests.  (purchasing live rock that’s already cured will speed up this process tremendously).

If you purchase your rock online, during shipping, there is a period of die off on the rock which is essentially poisonous to fish. It puts off tons of nitrates and ammonia, which is exactly what you do not want in your aquarium water.

All rock must be 100% cured before you can add fish. This is one huge benefit to purchasing live rock from your local fish store, which saves your 4-8 weeks of time curing your rock in a separate aquarium from your livestock.

This graphic shows the denitrifying process of harmful bacteria:

 Click here to see other explanations and graphics for the denitrifying process

Building Your Community

The first question to ask yourself is whether or not you want to keep corals. Corals add, among many other things, beautiful colors to your tank. They require proper lighting, filtration, and water flow, as well as specific water parameters. Coral Reef aquariums also thrive with a protein skimmer (which constantly cleans the water). While Corals bring exquisite life to your marine aquarium, there are many types of fish that are not reef safe because they eat corals or invertebrates. Tropical fish are classified as reef safe, caution (keeping with coral), or not reef safe. At the bottom of this chart you can see which fish are reef safe with Corals. 

When deciding the types of fish to keep in your marine aquarium, it is important to keep in mind the full-grown size of the fish, and how much space it needs and can share. A general rule of thumb: you need 2 gallons for every inch of full grown fish. The full growth size of a fish, its activity behaviors, and its feeding/waste production are some of the most important factors to consider when choosing the fish you keep. For instance, some fish are extremely finicky eaters, such as the Mandarin Dragonette which often only eats copepods (copepods are essentially like a bug that crawls around on the rock).

  It’s just as important to choose types of fish that are compatible with each other. Generally, unless you have a very large aquarium, its best to only have one Tang in your community. Damsels are another fish that don’t do well in an aquarium with their own kind. Most schooling fish, such as Chromis, prefer to be in odd numbers of 3 or more. It is beneficial to have some sort of bottom-dwellers in your aquarium (i.e. Goby or Jawfish) because they help stir up the sand, keeping the water clean of leftover food. Many types of fish don’t get along with one another, so it’s important to understand the needs of each type of fish in your tank (fish compatability chart). At Coastal Reef we aim to be an ongoing resource to our customers to help answer any questions or issues with sltwater aquariums, especially with regards to building a compatible and productive reef community. You can stop by our store in Wilmington, NC, call us at 910-792-6003, or email us at if you need help with any aspect of reefkeeping.

Other Resources about starting and keeping a saltwater aquarium:

www.carolinafishtalk is an online forum with hundreds of Saltwater enthusiasts who can help answer your questions and discuss the hobby.

Leave a comment

Please note, comments must be approved before they are published