Deciding what you need to set up a marine aquarium can be broken down in to two basic categories, essentials & things that are nice to have. What you need will also depend on what sort of system you are planning on running, fish only (FO), fish only with live rock (FOWLR) or a reef tank.

Essentials for a fish only system would include:

Fish Only With Artificial Reef
Fish Only With Artificial Reef
  • A water tight tank
  • Mechanical filtration
  • Power-heads
  • Basic salt
  • RO/Di water
  • Heater(s)
  • Basic lighting

Essentials for a FOWLR would include:

  • Everything listed above
  • Live rock/biological filtration

Essentials for a reef system would include:

Mix Reef
Mixed Reef Tank
  • Everything listed in the previous categories
  • Lights upgraded to reef compatible lighting
  • Reef standard salt
  • As you progress you may find that dosing systems become an essential part of the aquarium, but initially they are not essential.

Things that are nice to have on each system would include:

  • A skimmer
  • A reactor or two
  • A refugium
  • Auto top-off system
  • Sand is not an essential, nor is it nice to have in some peoples opinions. It is best to research the topic of sand versus bare bottom aquariums and make your own mind up.

The Essentials

When we start to break down the essentials, you can see that you can start quickly and cheaply with a fish only system, and then upgrade your tank through to a reef system fairly easily at a later date.

A Water Tight Tank

A water tight aquarium is an absolute essential for your new system. If you are buying your tank second hand, it is best to check that it is water tight by filling it up outside your house and leaving it there for 24 hours or more. Before you buy, be sure to check the seals around the aquarium for any damage and re-seal the tank if needed.

Mechanical Filtration

There are a few types of filtration available to the saltwater aquarist. You can use hang on back equipment, canister filters or sumps with filtersocks and sponges. Each filtration method has its own advantages and disadvantages.

Hang on back equipment can look a little unsightly, but they are great for people who don’t have the space for a sump or canister filter. The are capable or running a nano/small reef aquarium.

EFX 300 Filter
Canister Filter

Canister filters can run a full reef aquarium, you may need to have multiple canisters depending on how big your aquarium is. They can be quite loud and require a rigorous maintenance schedule, but they are a great option for people who want to run a low tech system or people who don’t have the space for a sump. They can also house your biological filtration along with your mechanical filtration.

Sumps offer more space for more equipment. They keep most of the unsightly equipment away from your display tank as well as giving your tank extra water volume. The more water you have available the slower any changes in your tanks parameters will happen, which will give you more time to react and deal with any potential problems. Sumps do require more space & can be annoying loud with the sound of trickling water and gargling coming from the weir.

Sumps are generally considered the best option for saltwater aquariums, but there are many successful reef tanks run on both hang on back and canister filters.

Power-heads & Wave Makers

Powerheads/wavemakes are an essential part of the saltwater hobby. Good flow in any aquarium is an absolute must to help prevent algae break-outs, increase the oxygen in the water, help reduce dead spots within the tank, help reduce detritus build-up & provide a more natural habitat for your tanks inhabitants.

Power Head
Power Head

By using power-heads to break up the surface of the water and remove any films that may have built up, you help to increase the rate of gas exchange in your aquarium, which increases the amount of oxygen in the water & helps to reduce nitrates.

If you are aiming for a reef tank, most corals will require some sort of flow. SPS corals tend to need higher flow than most other corals and flow will not only keep the nasties from building up around your corals, but it will help filter feeders get the food they require from your system. Having adequate flow for each of your corals will make or break a reef system. please research each corals flow requirements before placing it in your aquarium.


The topic of salts can seem like a bit of a minefield, there are so many options available on the market. The cheaper salts tend to be more suited to fish only or fish only with live rock systems, where as reef systems need more trace elements which tend to be found in the more expensive salts.

Different water hardness and trace elements will react with different salts in different ways. My best advice is to research a couple of different salt brands, see what other marine keepers say about the salt and if you’re happy with what people say about it then give it a try. You can always switch salt brands at a later date if you discover you are missing something or have too much of something.

RO/Di Water

Finerfilters RO Unit
Finerfilters RO Unit

Some people will tell you this is not an essential. I am going to tell you it is. Using RO/Di (reverse osmosis/de-ionised) water will reduce the number of total dissolved solids within your aquarium, which not only makes the water safer for its inhabitants but it will also reduce the chances of you having algae issues, reduce the chances of you adding copper to your system, reduce the chances of adding more nitrates to your system & help you keep more stable water parameters.

Marine keeping is all about keeping pristine water, the fish, corals and inverts are a happy bi-product of being able to keep high quality water and the only way to do that consistently is by using RO/Di water.

You can buy RO/Di water from most reputable fish stores or make it yourself with a home install system. You can read about my experience with buying an RO/Di unit here >>>


Heaters are usually the first thing to break in an aquarium. They either get stuck on or get stuck off, the latter of the two is the more preferred, but less common, outcome. Because of this dreadful habit they have of failing it is generally considered best practice to ensure you always have a spare heater around & that your replace your heater at least once a year, regardless of reliability claims.

Heaters are essential for helping to provide stability in your marine aquarium. Swings in temperature will stress both fish and corals, heaters will help ensure your tank remains within a 1-2°C temperature range, helping to reduce stress levels within your aquarium.


There are many different lighting options available to the marine aquarist. Basic lights to suit a fish only or FOWLR system are not very expensive, but reef standard lighting can carry a heft price-tag.

With so many options available on the market, it would be impossible for me to discuss the pro’s and con’s of each type in one blog. Lighting becomes far more important when you decide you want to keep corals than if you are just keeping fish.

If you are looking at a reef tank, speak to other reefers who have tanks of a similar size to your own and ask them what success they have seen with their particular lighting set up. There are plenty of review sites and forums that will allow you to make a budget friendly & informed decision.

Live Rock / Biological Filtration

live rock
live rock

This is all about the cycle within your aquarium. Fish waste & degrading food produces ammonia, ammonia is turned to nitrite, nitrite turned to nitrate. The bacteria that converts these toxic substances lives on hard surfaces such as rock. Live rock is highly porous rock that has a large surface area (even within the rock) to house the bacteria required for the nitrogen cycle. You can read more about the nitrogen cycle here >>>

If you are running a FOWLR or reef system, live rock is an essential part of this system to remove the ammonia and nitrites from your system. It is also a refuge for your fish, inverts & critters such as copepods to hide in, giving them natural shelter and helping them to feel more secure.

The Nice To Have Bits

A Skimmer

Protein Skimmer
Protein Skimmer

This was a tough one to add to the non-essentials list. Most reefers would consider a protein skimmer to be absolutely essential to running a successful reef tank, but there are plenty of very successful tanks out there that do not run a skimmer, so I couldn’t add it to the essentials list!

Protein skimmers help maintain low nitrate levels by reducing nitrate buildup. They remove organic waste before it has a chance to break down and release nitrogen compounds. A good skimmer can help reduce the need for water changes & improve water quality.


You can run different medias within reactors such as carbon & GFO. These reactors can help keep your trace elements in check & reduce things like phosphate & nitrate depending on the media you choose to run in them.

These are not essential parts of the system, but the will help reduce the amount of water changes and maintenance you have to do on your aquarium.


A refugium is a great place to grow macro-algae to help reduce the chances of an algae out-break & they provide a safe-haven for critters and pods. They can also be great places to increase your biological filtration capacity away from your main display, helping you avoid a cluttered look within your main tank.

Auto Top-Offs

Auto Top-Off systems reduce the amount of time you have to spend re-filling your tank with fresh water as the saltwater evaporates. Saltwater will evaporate, but the salt will not. To maintain your salinity levels and a correct water level you will need to regularly top up your aquarium with fresh RO/Di water (NOT SALTWATER!).

An Auto Top-Off system will kick in and top your tank up once your water level reaches a certain level. It will save you time and stop you from letting your water levels get so low that your return pumps run dry.